Here is a disambiguation page for new-comers. Feel free to reply with more or recommend different links for existing ones and I can edit this post to include everything so it's all in one place. I've split the acronym/term list into four categories: people/places/things, techniques talked about in MCTB, other meditation techniques not talked about in MCTB, and actualism. I've tried to provide the links most relevant to each category, so the MCTB links all point to MCTB, when possible, the non-MCTB links point to the respective technique's webpages, when possible, and the Actualism links point to the Actual Freedom Trust website.

Places/people/things:
BG: Buddhist Geeks
Bhante G: Bhante Gunaratana, known around these parts for writing "Mindfulness in Plain English".
Bhante V: Bhante Vimalaramsi, of Dhamma Sukha fame. Wrote a book about his take on Anapanasati Sutta
DhO: the Dharma Overground (this forum)
DI: Daniel Ingram, author of MCTB
HP: the Hamilton Project blog
IMS: Insight Meditation Society, vipassana retreat centre in Massachusetts, USA
KF: Kenneth Folk (see KFD)
KFD: Kenneth Folk Dharma, pragmatic dharma forum emphasising Kenneth Folk's 'Three Gear Transmission' approach. Also Kenneth's personal website

MCTB-related:
1st Path/2nd Path/3rd Path/4th Path: Usually refer to attainments as described in MCTB here.
3Cs: the Three Characteristics, also the insight stage
4NTs: the Four Noble Truths [1] [2]
A&P: The Arising & Passing Away (insight stage) [1] [2]
DN: the Dark Night (the insight stages)
EQ: Equanimity (the insight stage)
MCTB: Mastering the Core Teachings of the Buddha, Daniel Ingram's book
MCTB 2: Working title for project to update and expand on MCTB with assistance of DhO members. Also called 'Remastering the Core Teachings of the Buddha'
Mushroom Factor: a term Dan Ingram & a friend quoted to denote the cultural aspect of not openly talking about attainments and real insight, described in MCTB here and here.
N8P/TN8P: The Nobel Eightfold Path: Right (View, Intention, Speech, Action, Livelihood, Effort, Mindfulness, Concentration). Mnemonic: VISA-LEM-C (vee-sah-lem-see). [1] [2]
NS: Nirodha Samapatti, 'The Cessation of Perception and Feeling' (temporary attainment) [1] [2]
SE: Stream Entry (aka 1st Path)[1] [2] [3]

Non-MCTB-related:
6Rs: Technique taught at dhammasukha.org: Recognize, Release, Relax, Re-smile, Return, Repeat
DO: Dependent Origination (not talked about in MCTB 1) [1] [2 (pdf)]
MBSR: Mindfulness-Based Stress Reduction
RAIN: Recognize, Accept, Investigate --> Non-Identification, a meditation practice introduced by Michele McDonald.
TM: Transcendental Meditation

Actualism-related:
AF: Actual Freedom [1] [2] [3]
AFT: the Actual Freedom Trust, usually used to refer to the Actual Freedom Trust website
EE: Excellence Experience
FAS: Fatal Attraction Syndrome
HAIETMOBA : How Am I Experiencing This Moment Of Being Alive ("Note: asking how one is experiencing this moment of being alive is not the actualism method; consistently enjoying and appreciating this moment of being alive is what the actualism method is")
OFC: Out-From-Control ([1], [2]), as opposed to In-Control (#1 on this page), in reference to Virtual Freedom
PCE: Pure Consciousness Experience [1] [2] [3]
VF: Virtual Freedom

DhO: Dharma Overground, this forum
IMS: Insight Meditation Society, vipassana retreat centre in Massachusetts, USA
KFD: Kenneth Folk Dharma, pragmatic dharma forum emphasising Kenneth Folk's 'Three Gear Transmission' approach. Also Kenneth's personal website
MCTB: Mastering the Core Teachings of the Buddha, Daniel Ingram's book
MCTB 2: Working title for project to update and expand on MCTB with assistance of DhO members. Also called 'Remastering the Core Teachings of the Buddha'
NS: Nirodha Samapatti (sp?), 'The Cessation of Perception and Feeling' (temporary attainment) [1] [2]

(Feel free to modify, Beo. I'd put all the acronyms into alphabetical order if it were me)

Buddhism
DO : Dependent Origination

Actualism
HAIETMOBA : How Am I Experiencing This Moment Of Being Alive ?

Good stuff guys! I had run out of ideas initially but that was a bunch more. Keep 'em coming.

TM - Transcendental Meditation.

Great idea Beoman!

MBSR: Mindfulness-based stress reduction

Ok, so far so good.

No what about when someone says, "I entered 4th path, I entered 2nd path"?

All these numbered paths are also Acronyms

I would possibly suggest that you take a look at some of the most basic information posted on both the wiki and other threads if you are looking for this kind of information.

Not to sound overly antagonistic, but we have had some trouble with people getting on this site and trying to inflict trouble and confusion (aka trolling).

May you be happy and safe.

Also, I say this because your post above and others I have looked at do not resemble the usual types of first posts I usually see from people.

I am quite sure, however, you have legitimate reasons for being on here and I wish you success with finding what you are looking for.

ADR I dont think we have to try too hard to sniff out trolls, if they want to troll, they'll start trolling. The whole idea of trolling is to get attention so they aren't going to be too sneaky.

What kind of a legitimate newcomer says "Ok, so far so good." to a post going above & beyond addressing something they asked? Still it wasn't a bad idea so I included a reference to the paths.

Idk haha, it's just that James's usual approach includes far more obscenity.

The Eightfold Path:

This is the mnemonic I used to memorize the skillful 8: VISA-LEM-C. I pronounce it "vee-sah-lem-see."

1. View or understanding
2. Intention or aspiration
3. Speech
4. Action

5. Livelihood
6. Effort
7. Mindfulness
8. Concentration

Cool thread, Beo.

Bhante V: Vimalaramsi

other Bhantes ???

Claudiu this doesn't make *any* sense lol. What kind of legitimate host treats their guests with such presumption?

CCC, what the hell are you talking about? Do you even realize how silly it looks when you make such sweeping generalizations? I mean, when you actually contribute something from your experience there's often a lot of value in it. If nothing else then it's an honest report.

Seriously guys, sheesh

Bhante G: Gunaratana

Got it jake. So I deleted my stupid remark.

HP - The Hamilton Project blog

I know it's not an Acronym, but one thing I didn't understand when it was mentioned was the term "The Mushroom Factor", because the first time I read MCTB I skipped the "asterisk chapters", and that's where they are explained.

Not a bad one to include here. I've re-titled this the acronym & terms thread =).

RAIN stands for: recognition, acceptance, investigation, and non-identification.

What context is that in? Where did it come from, I mean? What would I link to in association with it?

RAIN: recognition, acceptance, investigation, and non-identification. It is a way to look at vipassana meditation. Recognition: I am aware of the itch on my nose. Acceptance: I will accept the itch as it is without avoiding it. Investigation: I will look closely at the itch. I might see it vibrate or turn into a desire to scratch it, for example. Non-identification: the itch is not me. It is an object experienced by...

I don't know who came up with it.

jack

Michele McDonald.

Alright, I've put it in there, even though this is the first I've heard of it on these forums. Might as well though!

Forgive my ignorance, but I've seen the term "OP" used a number of times. Can someone enlighten me to its meaning?

Without context I can't be sure, but I think it means "Original Poster", as in, the person who started the thread. That isn't specific to this board.