As has already been said, lots of people use snowmobile trailers. They work fine to a point. I ran one for about 4 years. Went on a 1500 mile road trip lightly loaded and went through 4 tires, 2 were brand new halfway through the trip and trash when it was over. If you don't pull long distances they hold up fine but you need to go slower or you'll overheat them (experience).
Those trailers are typically pretty easy to modify - add tongue length and sometimes even deck length. You can also usually modify to take 12" or 13" "normal" trailer wheels by shimming under the axel or flipping the axel. Look at what your going to buy and see if it will be relatively easy to modify.
I think the best thing is to modify utility trailers, like Cataraftgirls, or other folks that are sure to reply. They usually take the simplest mods and are easily converted back to utility mode for your random trailering needs. That's what I have done most recently.
Another option is to modify an old boat trailer. It can be relatively simple depending on your skills and imagination. If you or a buddy doesn't weld, it's probably not going to be cheap though. I did that for a friend 2 years ago and he loves the trailer, has $700 into it all told. It's simple, light (like 300 lbs) but less flexible than a modified utility and harder to adapt. It runs on 12" tires and is lower than most modified utility trailers.
Look at the trailer porn thread. There are lots of ideas there if you're the tinkering type.
"If you dont do it this year, you will be one year older when you do"