Adventure Time is a fun show.
Regular Show, Gravity Falls, and believe it or not the new CGI version of Ninja Turtles are good too.
I like this trend of funnier, nerdier cartoon shows that appeal to both kids and adults but lack the vulgarity or cynicism of something like Family Guy or Aqua Teen Hunger Force.
I guess they're the modern-day equivalent or something like Rocky and Bullwinkle.