free-personal/paid-commercial licensing model
noodle: as a licensee, i would suggest that you not bother.  too many people are dishonest about it, and too many things blur the lines between personal and commercial usage.looking back at it, i've installed something intended for personal use, but later on used it for commercial use, totally forgetting about the license agreement. one product in particular, i can think of, i would've paid for if i would've remembered.  but they went under.  probably from the license that few paid for.instead, i would suggest you offer two version, a "lite" version for free and a fully-featured version for $$$.