#1.

#2
Gee Oh Gee, here.
If I talk about it aloud with somebody, though, I just say Good Old Games.

# 1, as in LOG
http://www.youtube.com/watch?v=hP0kWqJJZa4

First 2 options:
1 for when I am around those who know of it.
2 when I'm talking about it to someone who doesn't know what it is.

#3:

I dunno much about linguistics or phonetic alphabet, so those who know either Japanese of Finnish pronunciation (Finnish is sometimes kinda like Japanese, or then my Japanese is just that bad), use that to read the pronunciation stuff (the g may be a bit harder than in Japanese):

Usually I just say "gog"

Then when people show their confusion because it's not an easily heard/understood word, so I say "Gee Oo Gee" (not English pronunciation) immediately followed by "Good Old Games", the latter pronounced in bad English.

Then I usually get lazy and start calling it "goggi" or "gokki" for ease of pronunciation and maximum heresy, and sometimes "gokkom" or "gog piste kom" (piste being dot in Finnish, and the "st" isn't "sute" even if I said something about Japanese).

In Poland, we usually pronounce like this: /gɒg/ (similar to UK's word God. Coincidence? I think not!)

Usually #1: GOG (or GOG dot com), though if I'm talking to someone who doesn't know the site that well I just use "Good Old Games".

I go with GOG like in LOG (so #1) but to make myself distinct from some members here (ant to annoy them as well) I make sure I pronounce it sounding like it is GoG

So it sounds: GowOG

I pronounce it as in "Oh my Gog."

Praise the Gog!

GOG as in dog. There is no other way.

Also, GOG members are Gogers. Spelled with one G, but pronounced Doggers.