As a touring cyclist I have some experience with hauling gear over distances. Personally, I prefer panniers for gear on a bike, but I do have a Burley trailer for my kids. Burley also makes a cargo version. They are probably the best of the two-wheeled trailers.

As our British friend mentioned, the BOB trailer is another touring favorite. Very well made but with only one wheel. This makes them track very well off road, but less experienced riders may have trouble with them.

There are even serious cargo trailers that some of my friends (who live car free) use to move refrigerators and the like with their bikes. Bikes at Work

Before you start hauling loads though, check your gearing. If you try to pull any weight with standard road bike gearing, you will destroy your knees at the first small incline. Proper gearing is important, even with relatively light loads. Low gears and high cadence will save your knees and your legs for the long haul.

I usually carry under 50 lbs of gear touring (plus 30ish for the bike), but I know people that carry 120+ while "expedition touring". One of my friends rode out LA during Katrina. He cruised past miles of cars sitting on the highway while pulling a trailer. Much faster than a car in that instance.

I have found that riding pulling my daughter to be pretty good training. She just turned 5 and with the trailer weighs about 50 lbs. You can definitely notice that on the hills. I have never pulled our dogs, but they are about the same weight and would probably work out about the same.

Unfortunately, it can be hard to find a bike shop that carries decent touring gear. There isn't much profit in it, so I can't blame them much. Without a good shop though, it can take a bit of trial and error to find the gear that works best for you and what you want to do with it.

Greg