Portal because of the songs in the credits, they're just too awesome and are great for karaoke.
Otherwise, anything that has you do something during the credits. I don't want to sit there and read a ton of names whilst listening to music, I want to do something interesting. Add in something for me to do, I don't entirely remember but I think Guitar Hero had a song you could play whilst the credits rolled and that's a good example, and I'll go through them. Otherwise, if it unlocks something I'll go away and make myself some food rather than watching them, and if it doesn't I'll skip them.