I actually find AngiesList and ServiceMagic hit or miss.
Sometimes someone will get a good review and it turns out bad or costing more. I used a contractor once off of one of those services... once.
I prefer person-to-person referrals (although some persons on TI could be suspect). And even that isn't infallible (yes Homer... I'm looking at you!
).
@bearman: Doing a slat fence is actually pretty easy... you just need patience for all the measuring/cutting but once that's done, dropping the footers and attaching the slats is actually fun (but that was using a nailgun... not too sure about drilling in vinyl slats).