I did an informal survey of friends and a couple of quick searches to see what free Apps might interest me. I amassed almost four screens worth of Apps; I've listed those that are work related below...
AroundMe - For lunch near a client site
Citibank - Business finance
Coffee Finder - For Starbucks near a client site
Free RSS - To stay on top of my favorite blogs
Free Wi-Fi - Who doesn't need free WiFi?
LinkedIn - To stay connected with business associates
MileBug - To track my mileage (the only App I've purchased, $1.99)
RDP Lite - Remote Desktop client
Restaurants - Shows calories at chain restaurants (a.k.a. what not to eat)
Skype - Communicating with customers
SubnetIT - Subnet calculator
Units - Conversion of Power, Data Storage, etc., from one metric to another
Urbanspoon - For lunch near a client site
WordPress - Keep an eye on this blog