I bought the little 8 gallon 2HP compressor for use in the garage. It is oil cooled, very loud, but works well. I think I got it on sale for $90.
Of course, it was a project: I had to adjust the cutoff pressure because it slowly worked itself down to cutting off at 105 lbs and not kicking in until it reach 80lbs. It is rated at 115lbs, so I adjusted it up to 120lbs. Now my framing nailer always has at least 95PSI available to it. Actually, I think I need to adjust it again.
Oh, yeah, it is portable enough that I was lugging it around to various projects around the house. My 60 gallon compressor doesn't lend itself to moving around, and 200 feet of air hose is just too much to deal with.
The main downside is that it won't start up if you are too far from the breaker. I have to run 12 gauge extension cord to a 20A outlet near the breaker in the garage. I have successfully run it on 160 feet of 12 gauge extension cord, though. Also, I have a Honda EU2000i generator, and that will not power the compressor.
On the other hand, I picked up a used Porter Cable 2 gallon 1 HP 150 PSI compressor off Craigslist for $100, and it came with a free brand new brad nailer. The PC is quiet, will run off my generator, is very light weight, and doesn't require fiddling with the cutoff.
The 8 gallon HF compressor does just fine with my impact wrench: I haven't tried the 2 gallon PC compressor with the impact wrench, but I suspect it may have trouble keeping up.