hucklebarry: I find the definition to be debatable ("1. (of a creative work) referring to itself or to the conventions of its genre; self-referential."), but I would consider the Book of Unwritten Tales to be fairly meta in its dialogue and humor.

It spends a considerable amount of time making fun of computer games and the things most computer game players would find interesting. (RPGs, MMOs, star wars, etc.)

I'm also a big fan of games within games. (which could be an acceptable definition of meta). Some of those are:

Spheda (golf) and fishing in Dark Cloud 2. (fairly robust feature sets as well).
Doom 3 lets you play an arcade game within the game (single clicking, not fun for long).
From what I understand some games let you play entire games from within them (day of the tentacle)

... sort of like world of world of warcraft... have a feeling this will happen ;) (https://www.youtube.com/watch?v=Rw8gE3lnpLQ)

flummoxed: Yeah, it's just the way I refer to these kind of games, it's hardly a technically correct term :D
Lol, that video :D

hudfreegamer: Assassin's Creed:

You're playing as a genetic memory.

Mr.Caine: Commentary on violence in video games.

superstande: weelll... I'm not sure if this is what you are looking for. But Simon The Sorcerer 1 and 2... Especially the second one has some funny things metawise. You just need to play and see what I mean. Brilliant dialogue.
Also The Secret of Monkey islands. How do you know we are pirates? It says so when I point you with mouse pointer :)