No One Knows goes down pretty well in my experience.
Sweet Home Alabama gets some laughs, especially if you whack on a strong Deep South accent.
People my age tend to know some Offspring songs, RATM, Linkin Park.. cheesy stuff we used to listen to as kids that's fun to pick back up.
You really need to gauge the situation properly, and it can be difficult. As we've seen, some people hate people playing guitar at parties no matter what because hating things is cool and lets people know you have opinions about things. You have to play FOR the crowd and not AT them, and you'll need to know songs that will appeal to them which differs from crowd to crowd.
Some of the best times I've had at house parties have been when a few musicians have been left up and we've torn songs apart with improv instruments and new 'improved' lyrics, but you need to be with the right people to get that going. A lot of boring ***** would rather veg out.