It seems that no matter how many pixels I have to play with I could always use more. Consider this number of apps that I have open a day:
Browser window with debugging pane (1200 x 1200)
Skype (220×1000 high) with conversation window (400×600)
Text mate or vim (typically 1600×1200)
Terminal windows – at least two. One for Git and one for python shell. (1600×1200)
2nd browser window for looking stuff up though I can use tabs for them.
Could also do with having an irc client, finder and adium but I usually close them.
It all equals too many pixels