I second Scan2PDF. Nice to be able to save a map/blueprint or a note the customer gave you. I then put it in DropBox or Evernote and add it to the customers information in ACT.
Speaking of ACT, I use CompanionLink to sync my contacts and calender with Google, which updates my phone. When I get to a customer site, I just log in and out via my Droid.
Pandora is nice...
AndFTP is a nice way to sync with an FTP site.
Bria softphone for Droid. Use it when I'm around the office to tie into our phone system.
SIP-Driod as a general free softphone.
Not business related, but I really like YouVersion for the Bible. You can select most any translation you want. "No Pastor, I'm not texting while you preach..."
I really like having a construction calculator around. When my last one got stolen I was able to download an app from the same people who made the old one. Measure Mastor Pro from Calculated Industries.
A office calculator app is also nice.
Of course, you must have Kindle on your phone. When you get stuck at a site waiting for someone else, you always have something to read.
TiKL- Touch 2 Talk- is a nice walkie talkie app. Works well for testing cables.
As Travis mentioned, Wifi Analyzer.
As my buddy Tim said, PDANet is nice. 2 Years ago I paid 60/month for an air card with Verizon. Then went with Virgin Mobile for $40/month. Now I use my Droid when needed for no extra charge. (BTW, I really like Virgin Mobile)
