I use 9 screens. I constantly d/l and delete apps to see what's useful and what's not. Some I keep around just "because". Other than the first 3 screens and a couple "utility" screens that I use the rest is just fun stuff I'm tryin out. I figure hey if you have the space then why not use it
Also, one thing I found interesting from the other users pictures is the bottom 4 apps that are used. Other than the phone app (wished you could move it cause I'd replace it with SMS) I have to have mail available, the calendar and safari. Interesting to see what users deem important to have access to regardless of what screen they are on
Here's my breakdown:
Screen 1: Apps I need and use just about everyday. I dont use Midomi everyday but I hate trying to find it or Shazam when I'm driving and a song I dont know comes on.
Screen 2: Things I use just about everyday as well but include games and my horoscope and magic 8 ball.
Screen 3: Web shortcuts to pages I visit often. Notice the TiPb

and the Full Google Calendar is nice to have a shortcut to.
Screen 4: Crap and stuff rarely used.
Screen 5: Language utilities. Probably should move these up a screen.
Screen 6: Calculators, money converters, etc. Probably should move these up too.
Screen 7: Crap
Screen 8: More crap
Screen 9: Yet even more dookie.
Hey like I said I am a packrat. People complained about not having apps on the 2g and now that we have 'em I tryin out whatever I can. Now that 2.1 is out it doesnt take forever to sync anymore
Apologies about the short novel here!