I have a Coleman Powermate 1000 (850W nominal/1000W surge).  It's a
2cycle that comes with both 110V AC hookups (2) and a 12V battery
cable for 12V charging.

It's great for the light jobs like boosting a weak battery after
sitting at camp, running a dirt devil vacuum, small power tools
(drill, etc).  In fact, I get too lazy to run a 100 ft power cord
from my house sometimes when vacuuming, so I fire it up.  It has an
autothrottle, so when you need more juice, the RPM go up.

I got a reconditioned unit from Damark for just about $350 with
shipping.  You have to premix gas and oil, but that's easy with a
little 1 gal jug.

I would consider this unit light duty; if you want to run big air
conditioning units and such, you probably need a bit more power.

And yes, contrary to safety precautions, I do carry it inside the
van.  It goes behind the middle seat in our non-poptop Weekender.

-Karl

Karl and Kristina Bloss, Trexlertown, PA
'87 GL Weekender  "Beverley"
VW shop list: http://www.enter.net/~bloss/vw/vwshops