I have an HTC Hero from Sprint which is currently running Android 2.1. It really is a great phone (and one of the first true geek's answer to the iPhone).
I am making this list for posterity sake... and in case I decide to wipe my phone or someday upgrade (the EVO looks pretty sweet, doesn't it?)
This game looks simple at first, but it's enjoyable (and a great way to distract children in a pinch). Use the accelerometer to help bounce cows and other farmyard animals to freedom from UFO's.
Has NIV for free, but it's web based. I only have this because CadreBible doesn't have the NIV (yet...)
Has a host of free and paid bibles, commentaries, references, etc. I especially like being able to switch from a verse in an english translation straight to that verse in another translation or language (greek, hebrew, latin, etc). It also includes some nice study guides if you are looking for that sort of planner.
demoPlayer (RockPlayer beta)
Plays most any video format you would want on the Hero. Currently the beta is free.
For RPG enthusiasts, if you forget your die-20 at home, no worries!
Free (up to 2GB) file depository that lives in the cloud, sync files between your home PC, work, and now your Android phone, too!
ES File Explorer
E-Strong's file explorer. It lets you explore the file system on your phone. Self-explanatory.
Free universal note-taking that backs up to the cloud and syncs between your phone and PC, too.
A chromatic tuner for guitars and other instruments. Great!
A secure database for remembering your passwords. Functional and free.
I know, it's a stock app, but I use this literally every day on my walk to and from work to listen to podcasts. And it sync's with Google Reader, too!
Google Maps with Navigation
Google maps added walking, biking and public transportation directions; Google Buzz for finding local hotspots; and free turn-by-turn directions with GPS navigation.
You have an audio file. You want a ringtone (or a notification sound). Also does cropping.
The free version is a pretty fun strategy game, or pay for additional maps, difficulty levels and tools. This is the only app I have paid for.
I use this for those times when I hear an awesome song on the radio and simply need to know who and what it is.
Google Shopper & ShopSavvy
Comparison shopping by scanning bar codes.
The Weather Channel
I use this every morning to determine the weather is appropriate for walking to work, or requires some alternative method to transportation.
At the moment, my favorite twitter client. Does everything it needs to do, and it's free.
Helps to find wireless access points on the road, and at home to plot which channel has the least interference in my condo building.
Gives me mobile access to the xda-developers.com forums, for all my Android news and hacking updates ;)