I have many of the EXTRAORDINARY apps already suggested (Beautiful Widgets, Locale, Docs2Go, etc). So here are a few unmentioned.
PhoneMyPC - Holy Crap! This thing can turn your phone into a trackpad for your computer!
Yeah so what? There's more. It can remotely take a snapshot of your computer's current display screen (in case you want to check up on your kids activities without fully diving into privacy violation?).
Cool, but wait, there's more! You can watch the actions of the display LIVE on your phone (in case you want to fully violate privacy? I dunno...).
Wait, there's still more. You can actually interact with your computer live, remotely (over 3G from wherever), in the exact way that you are thinking. Just click the 'Interact Live' button, and you can wake your computer, login, see your desktop on our phone, open whatever files you like, open your browser, do ANYTHING from ANYWHERE as long as you have a data connection! It is full remote access to your computer (a GREAT thing to have if you forgot to print or send a copy of that file on your home PC). I have even tried it to stream Netflix to my phone! (FYI, it only runs at 2fps and does not have sound... yet).
Mobile Fax - Use your camera as a scanner and your data connection as a modem and send up to 9 pages a day. Personally, I do not have a fax at home, but I occasionally find the need for one. Problem solved! Are you a construction worker (or other sub-contractor)? Do you need to fax an invoice to the head-boss before the end of the day? Pull out your phone and get it done in seconds!
Scan2PDF - Uses the camera as a scanner and converts the image into a PDF. This is great for students like me. Rather than xeroxing pages out of a book, I just snap a few PDFs as I flip the pages and I'm on my way!
OneClick widget (may no longer be available on the market) - A nice assortment of widgets to control phone functions. But what sets this one apart is the ability to customize the color scheme of the icons. ALSO, the airplane mode widget gives the option to leave the Wifi radio on!
Mini Golf Wacky Worlds - It makes me sad that the game only has 36 holes!
BetterCut - Helps to customize those icons for your desktop. Do you use 'Carrr Matey' or some other app with an absurd icon eyesore? Here's your fix!
Pure Music Widget - Various size widgets for controlling your android music player from the desktop
I hope that helps. ENJOY!