Well, my full time job is running/owning a custom woodworking shop. Aside from all communications (phone calls, emails, sales, etc) my phone has several apps that I find invaluable for daily use. Obviously contacts for all phone numbers, email addresses, etc... My most commonly used App has to be AK Notepad - I keep track of tons of notes here, from sizing measurements, questions from/to clients, to do lists, inventory lists, appointments (it does notifications with custom time setups) as well as reminders for just about every daily task - without AK Notepad I'd be lost! Better than my secretary (she's much better looking...).
Next is Docs to Go - here I carry my daily Excel spreadsheets, PDF's, and Word documents for "on the go" reference.
I also have my "cottage business" - manufacturing and selling
MIKRADLE, and for this PayPal Mobile as well as Pkt Auctions keeps track of my sales, inventory and messaging from buyers.
I guess I'd also have to mention Tipper - a calculation App for arriving at proper tips and breakdown when "wining & dining" clients during sales meetings..
I'd be lost in business without my Droid! It replaced my Palm, my camera (for on the job photos later used for pricing up quotes), my GPS, my iPod music player (listening to music on the way to/from appointments, as well as my old "dumb" phones!
mike