On my Hero:
Battery Widget: widget for the home screen with battery %
Apps Organizer: you can create program groups and put shortcuts to the group on the home screens. Very useful with icons for groups like games, multimedia, tools etc.
Beebplayer: iplayer/ live TV & good bbc radio player.
Ebuddy: Pulls online contacts from msn, yahoo, aim, googletalk, myspace, icq & facebook chat into one program. Very handy and will run in the background. Alerts you to messages like it would a text.
Facebook: App needs some more work to it and personally i still prefer the mobile site.
Layar: Search and shows what’s around by layering information on top of the camera view. Quite useful but doesn’t always seem to have all the information it could have one day.
Google Listen: Podcast search/ download/ listen. I really like it but haven't tried any alternatives yet.
NetCounter: Measures data transfer for wifi and 3g. Not sure how accurate it is but its a must have to get an idea of what your using. It will also alert you when you go over certain amounts.
SmsToMailbox: Forwards all your texts and call details to your email account. Great app especially as the Hero can sometimes miss some texts (on the original ROM anyway). Mine forward to a google account and get marked as read to save me getting new alerts all the time. I just check it every one in a while to make sure I’ve seen everything.
TasKiller: Kills apps you no longer need open. Alot of people upgrade to pro but I'm more than happy with the free version.
Xtremelabs Speedtest: purely just to see what speed I’m getting over 3G/WiFi
Tv-Guide: Great app for TV listings. Shows how far a film is through and you can set it to remind you before a programme starts.
Barcode Scanner: Great for checking online prices of DVD's etc when out shopping. Found it recognise the barcodes far easier than ShopSavvy.
MixZing: Media Player. Not too keen on it tbh. Yesterday it randomly started playing whilst my phone was in my pocket and the app had been killed with taskiller a few days previously. Cant be having that happen again.