I have a 450VA Coleman inverter in my Blazer, haven't used it very much. Most recently it powered a string of Christmas lights wrapped around the luggage rack.
If you have a laptop, the best solution is to get a 12V adapter for it rather than use the inverter. Much cleaner power, and a whole lot more efficient. I'm pretty happy with the Coleman, anything like that I always want to buy from somebody who will be around in case I need warranty support.