TeamCity is pretty cool because:

-it's very easy to set up and configure

-does not depend on one particular technology (we build our .NET site, android and iphone apps with it)

-there are some cool plugins available to extend it

(otherwise go heroku or appharbor)

+1 for TC. It's also got a free version which is enough for us.

http://www.jetbrains.com/teamcity/

All of which holds true for Jenkins too.

I have used both and prefer Jenkins mainly because it is free and open.