You can take almost anything that doesn't have a powerful motor or heater in it.
So, don't take your vacuum cleaner, washing machine, dryer, fridge or hairdryer.
You can take a TV and run it off a transformer, but it won't pick up any channels. Only do this is if you are planning on having a 'UK corner' in your house with a TV/VCR/DVD/Playstation fixed to PAL and Region 2.
Anything that can run off a battery is fine to take - so you can take rechargeable power tools, for example.
Small electricals with motors will work off a transformer, but they will wear out faster. It is probably better to take them and now rather than having to repurchase immediately because you aren't going to be able to sell them for anything.
If you take lamps with you, you won't be able to buy bayonet bulbs, but screw in are fine. All you have to do is change the plug. There's a good chance that you will need lamps (American houses of a certain age can be very scanty on overhead light fittings).
Computers are fine as they are DC and dual voltage.