I have a few jobs to do that would go easier if I had an impact wrench, but I don't have an air compressor or accesss to one.  I don't recall ever using an electric impact wrench... how well do they work?  Do I need an expensive one?

Not sure abotu the electric ones, but they have ones that u hit with a hammer that work pretty good.

I'd skip on the corded ones...although the cordless ones are awesome for low(er) torque stuff (e.g. most of the bolts on your bike) although they can pack enough punch to do just about anything. Go with a cordless 14.4 or 18v from DeWalt (preferably) or Makita. Very useful, you'll find yourself using nothing but.

I have not heard of any problems relating to electric impacts. We used to but them for our install crew when I did mechanical contracting. The cost is the down side. I was going to but a Dewalt but at around $200 I coould not justify the cost with the minimal use it would get from me. A guy at work bought a Harbor Frieght impact and he has no complaints. I think it was around $60 which is reasonable for the amount of use it would get. I would not get a cordless one unless you keep you batteries charged or are ok to wait for them to charge. Some tools are best to buy corded, anything high torque or long use.

Yeah, I was definitely thinking corded... I feel more tied down by batteries than a cord most of the time cause they always need to be charged, then you need wait for it to charge or buy more.  For how often I use it, I'll probably go the cheap route as long as they more or less do the same thing

I would very seriously think about getting a compressor.  I mean, you're going to be spending $100 - $150 on a decent electric impact that will not work as well as a $60 air-powered model.  Why not put the difference towards a compressor so you can also run an air ratchet, blow out your air filter, air up tires, run a nailer/stapler, etc.  Even a cheap compressor can handle all of those tasks just fine.  I just picked up an older Speedaire 3 hp unit for $40 on craigslist.  A new check valve ($15) and it's working great.

Update: Well I got an electric impact wrench and it is way more expensive than what I had planned... Only I didn't pay a cent for it.  Got it for my birtday; goes for around 250-300 new.  My dad got it for $5 on ebay though   INGERSOLL-RAND 8049

The guy said it wouldn't turn so my dad bought it figuring it was just the switch or something.  Turns out it works fine.  I'm guessing the guy just had it in between forward and reverse where it doesn't do anything.  Works great, I'd say it's the best $5 tool I've ever had

I have a Mastercraft Maximum (canadian eh?) 14.4v cordless impact wrench...they go on sale all the time for $100-$150, and they pack a punch. My batteries are two years old with almost daily use and I can go all day, 6 am to 10 pm using it constantly and I rarely have to use my second charged battery pack.