Good post, but what I really meant was...
Checks in dialog are usually against stats or Speech skill
When does it use Speech and when does it use stats?
Heh, oops. Well for starters some background for your previous question: it appears Fallout checks Speech a lot more often than Charisma. There is a check against Charisma in 17 scripts, whereas checks against Speech happen in 103 scripts. I didn't realize until I looked right now that it was that big a difference. Looks like I was wrong, Speech matters way more.
As for the original question itself, Charisma is checked:
1) Whenever trying to seduce somebody (Harry, Jennifer, Keri, Sinthia)
2) Sometimes alongside Barter skill check (meaning it's not unique at all, just a more realistic "stat-or-skill" type check)
3) Sometimes alongside Speech skill check (meaning it's not unique at all, just a more realistic "stat-or-skill" type check)
Which takes care of 10 of those 17 scripts. The other charisma rolls in dialog are:
-- check against strength-or-charisma to see if Bob doesn't want to pay his blackmail dues any more (if he was blackmailed and it's time to pay up),
-- minor difference in a dialog result with Demetre that has no impact on the game,
-- you can get pulse grenades from Michael for letting him know some chick has a crush on him (although I've been informed it's broken in the shipped version of the game)
-- if female, Rhombus can tell you a vague hint about the mutant army if asked for rumors
-- convincing the Vault13 water thief to come peacably (otherwise you have to kill him).
-- while talking to Rutger about missing caravans, seems like with the checks it's easier to get the job back if you fucked up or changed your mind
-- if pass the check, the Master will go into combat instead of giving you one more chance to get dipped (lol, i think they reversed this check on accident)
For other stats.... it generally uses a stat check when it "should", so like there's a few times in the game where you can threaten to kick their ass if they don't do what you want, and those are usually Strength checks instead of Speech checks.
Strength for threatening, Charisma for charming, etc. I don't really feel like digging through all the scripts to check the other stats, sorry. Not at this time anyway. If you search for the word "check" in Per's guide you'll find most examples of stat checks in the game.