Recommended
Software

Freshbooks Invoicing
I've just started using this to invoice my clients, and absolutely love it! Definitely worth a look.

Vertical Response
Build, send and track email campaigns in minutes with VerticalResponse. No contracts, no hosting fees, no monthly fees, no support fees. You only pay for email delivery. Reasonable prices & easy setup for graphical emails.

Ad Aware
This nice little free program seeks out & destroys advertising-tracking files & spyware on your computer. You'll be amazed how much of this stuff is on your drive if you do any amount of time on the net!
(Please note that this is NOT anti-virus software... you definitely need to have a good antivirus program installed & updated, and a personal firewall as well if you're hooked up 24/7 to broadband)

Geocaching
For pure entertainment value! An addictive little hobby that gets you out of the house to some very interesting place!