Although they won't tell you which parking services they use, I know that iMonetize (please use my signature link if you sign up) uses HitFarm. How do I know this?
I'm testing about 50 domains at iMonetize. I clicked over to one of those domains to see what it looked like parked and really liked the layout. I, too, found out it was from HitFarm. Unlike the site mentioned in a previous post, the pics shown on my domain were relevant.
iMonetize sounded interesting to me because their service is really more like a domain management system than just plain vanilla parking. Their system identifies where your domains are registered, when they expire, how many domains you have in each TLD, and some other stuff.
They claim to be able to optimize your domains not only for your domain keywords, but also for the particular parking services that pay the best for that particular domain--even down to the DAYS of the week when your domain does best at each parking service.
I've only been over there for a couple of weeks, but I'm liking what I see so far. If my domains won't be fully optimized for 30 days, then I'm looking forward to some pretty decent payouts.
Like most here at NP, I've used many different parking services. Others I like and use most (in no particular order) are TrafficClub, DomainSponsor, and NameDrive.
I'll try to remember to post my results with iMonetize after the first 30 days.
I'd be interested to hear what others have experienced at some of the parking sites I haven't tried yet, specifically ActiveAudience, Seguin, or UrbanData. Anyone?