Tether (wifi): http://code.google.com/p/android-wifi-tether/
Tether (usb): http://code.google.com/p/android-wired-tether/

Need root, and a phone with the correct routing tables (built into most homebaked roms).

For email, I use "K-9 Mail". For tethering, I use PdaNet, which does not require the user to "root" the phone.

I got BugMe which is kinda like sticky notes on Windows 7 for the Android Home Screen. I can't wait to get an Android tablet when they start coming out soon. It also sets alarms for notes.

Friday I downloaded & installed Weather Bug ($1.99 version not the free one) and it can put a widget Doppler Radar Map on the home screen! It came in handy last week when I was at ORD. Note: the map takes 4x4 space. But I'm tempted to have one home screen with maps for the various airports I need to go through this week. This is a static map and only auto updates every 3 hours but you can force it to refresh.

As others have said Google Voice, Google Maps/Navigator, Wifi and USB tethering.

SIPDroid for free VOIP calls from anywhere and a US phone number when overseas. But don't use the version in Market because it is disabled on 3G and EDGE to appease cellular operators. Instead download the apk from http://www.sipdroid.com/ and install it from your SD card.

And of course to install from your SD card, a good file manager would be helpful. As others have said, ASTRO File Manager, free from Market, is a must have.

Zillow's app, free from Market, is awesome for home buyers for its cool integration with Google Maps.

Mapdroyd (with a y), free from Market, is no competition for Google maps but is a great backup because it can download it's maps in advance and then works great off-line when you land is some third world country and are taking a taxi to your hotel with no data access.

Speed Test, free from Market, is a fun little app for checking up on your data rate performance under different circumstances.

And not qualifying as app's but pretty awesome for the more tech savvy types with rooted phones and voided warranties ;). Amon-RA's custom recovery from http://forum.xda-developers.com/showthread.php?t=611829 is a must have for changing ROM's and tinkering with other stuff you aren't supposed to tinker with.

And last but not least for the more tech savvy types with rooted phones and voided warranties ;) CyanogenMod's custom ROM's from http://www.cyanogenmod.com/ are generally really awesome and while their are many custom ROM's out there, CyanogenMod's are generally pretty polished and release quality. Have an old G1 and want most of the same new features of a shiny new Nexus One running Android 2.1 on your old beater? Try the latest CyanogenMod ROM.

The one in the market now does use the 3G network. Its not wifi only anymore.

Who do you use for your outbound calls for free?

That's good to know the version of Sipdroid in market is fully functional now. The app is allot more solid since the 1.4.7 release.

I route all calls through either my free Gizmo5 (not accepting new accounts at the moment) or free Sipgate accounts and then into Google Voice for the outgoing hop onto the POTS network. The trick is to use the free site sipsorcery.com to run a script on outgoing calls to transparently trick Google Voice into thinking it is doing a callback on outgoing calls. It is completely transparent in operation. I dial someones ordinary US number, it rings showing my Google Voice number as caller ID. No callback app or anything. Just Sipdroid. Although not technically necessary I also route outbound calls through a free account at pbxes.org en-route to sipsorcery.com. This has increased reliability dramatically and solves some issues with ISP's blocking VOIP.

It is crazy difficult to set up. Intensely complicated and needed allot of tweaking, and trying different codecs and such to get it all working smothely. But it works and now all calls through Sipgate, both incoming AND outgoing to USA are 100% completely free Google Voice calls. Completely transparently.

There are good write ups on the system here but it may still need a fair amount of tweeking to get it all strait.

http://docs.google.com/Doc?docid=0Ae...M4ZjNjeA&hl=en
http://forum.xda-developers.com/showthread.php?t=548405

If you enjoy a difficult technical challenge as a game like a puzzle, to keep your thinking sharp, it really is a super cool setup. If you are looking for free phone calls with no effort on the set-up, better to pay a SIP providers nominal service fee.

Are there any streaming radio apps besides iheartradio? I'm looking for streams of actual stations - not services like Pandora that stream MP3s.

I use iheartradio to listen to the Bob and Tom Show in the morning, but for some reason it takes up to 30 minutes to connect over 3g. Once it connects it seems to work fine, it is just the initial connection. Over wifi it connects in a few seconds. It also seems a bit choppy this morning (on wifi), but I think that might be the feed to iheart since I am getting the same on multiple stations throughout the country.

I think I will be able to stream directly from some radio station websites once flash for android is released.

Have a look at Radio Hamburg in the market. Yes, German, but plenty of english songs.

I really like Smart Keyboard PRO. I was missing the autotext feature in Blackberry and this lets me build a database of autotext entries again. Plus it's nicely configurable and has a much more pleasing look than the default keyboard.

Nothing beats the Swype Keyboard :D

Simply amazing.

If you can get it :( Not available right now except for a closed beta.

I'm always trying to swype my ipad, just keep forgetting and missing it on the iPad. Swype is awesome.

I have a copy that never expired, if you are interested PM me

It's a nice themed swype with blue blur when pressed

Mine
 

Where? which, based on your location recommends restaurants, area gas prices, coupons, traffic, news, yellow pages, and more

Yelp-- restaurant and shopping reviews near you reviewed by users

Mototorch- turns your little LED on for a nice bright light--and strobes and morse code :)

Advanced task Killer. It's amazing how many things I can have running without realizing it :)

Jewels. Always addictive game :)

OpenTable for dinner reservations

Weather bug free

Trip It--amazing and so helpful