Go to the applications folder, and click on the gear icon in the top of the finder window, and select Show View Options. In the window that pops up, click the "Calculate All Sizes" option at the very bottom. The -- will be replaced by application sizes.
There's always my method too. My method is Ctrl-click on each Application folder and click on "get info". This will tell you its size as well. However... it's the worst method here.
lol ipwitch, we posted in the same minute... if ur post was there b4 i started to reply, i wouldnt of typed my reply at all. just tellin all of ya so u dont think i was copying him/her lol