I guess it depends on the look your going for i use CS2 mostly to make screenshots look a bit more photographic.
Photoshop`s diffuse glow filter can add a certain something
(filters>distort>diffuse glow) + adding grain and using a sharpen filter can also improve the look of a screenie.
Auto-levels can also improve the overall appearance of a pic.
You can add lens flare too, just dont make it too bright or it`ll look rubbish!
(filters>render>lens flare)
+you can always desaturete the image to get that b&w look
.
++ The obvious one, before you even take the screenshot, make sure your settings are at their max, ie at least 4x AA and 16xAF (in your vid cards control panel)
A few of my shots:
http://i201.photobucket.com/albums/a...ris1066/p6.jpg
http://i201.photobucket.com/albums/a...is1066/p1t.jpg
http://i201.photobucket.com/albums/a...ris1066/p2.jpg
http://i201.photobucket.com/albums/a...1066/photo.jpg