Yes, I use the onscreen keyboard only for short SMSs and stuff. For e-mails, I'm always on the hardware keyboard. I've also setup my personal and office mail on it, and it also picks up the calendar syncing settings automatically which is great! If you haven't, do it!
Here's a few apps I think you should try -
Twidroid (Twitter client)
AndChat (IRC client)
Nimbuzz (all-in-one instant messenger)
Astro (file manager that can access network shares!)
Barcode Scanner (to scan barcodes and use those QR codes to quickly download apps / visit sites)
Astrid Tasks (to-do list with calendar syncing feature)
Layar (augmented reality)
My Tracks (for GPS)
Opera Mini 5
Google Sky
TaskPanel (task manager to close unnecessary services/apps)
And....for wallpapers, make them a resolution of 960x854 px ( I use 3 of those virtual desktops)