What version of android is it?? There is a firmware upgrade being circulated by HTC and phone operators taking the hero from v1.5 to v2.1 (loads more apps available for android 2.1)
Big memory card too (I've got a 4gb but should really go for an 8gb)
Calendar, email and contacts sync with your google account
If you want to show your phone off to people, download google sky map and wait for a clear night, turn on gps and mobile internet, go outside, wait for a gps fix and see what happens ;-)
Have you got sky+? there's a recent app from sky to enable you to set sky+ timers from your phone
Don't bother with any apps for wallpapers or lock screen images, make your own...
Wallpaper dimensions are 640w x 480h
Lock screen dimensions are 320w x 480h
To add new ringtones, connect your Hero to USB and mount the device on your PC. Create the following folders on your memory card:
/sdcard/media/audio/ringtones
/sdcard/media/audio/notifications
/sdcard/media/audio/alarms
(doing this stops ringtones etc being picked up by the library in music player apps)
There's a load of other tips done by Lekky and contributed by other hero users at
http://androidforums.com/htc-hero/20511-htc-hero-tips-tricks-useful-apps-v1-6-a.html
;-)
