Saturday Morning Breakfast Cereal is consistently funny: http://www.smbc-comics.com And the guy who writes it also works on this: http://snowflakescomic.com/ which can also be ok.

Of course, dinosaur comics is a must here: http://www.qwantz.com/

Moe is funny just about everyday, but is slow on updates recently: http://www.firmanproductions.com/

I also quite like Amazing super powers, and before it ended Perry Bible fellowship was one of the best.

I think xkcd is really not very good anymore, and this is better: http://xkcdsucks.blogspot.com/