I got a free package of the Huggies Little Movers Slip-On diapers through Bzzagent, so I gave them a try. I happened to get them right around the time by 2 yo decided to potty train, so it worked out great. I really like the diapers. They're basically the same thing as training pants, if you ask me, but come in smaller sizes. And they're cheaper.
These diapers are $9.97 for 23 (size 4) at my Walmart, so with a coupon, they are about the same price as the store brand training pants - and cheaper than the Pull-Ups. PLUS, they are really stretchy, and I found that I needed to buy a size 3, even though he normally wears a size 4. Buying a size down gives you an extra 3 diapers in the package for the same price. However, the smaller diapers don't hold enough, so if you're using them overnight or for a heavy pee-er, be aware.
We are pretty much potty-trained, but using these for long outings and at night. I'll keep buying them as long as I can find coupons to make them cheaper than training pants.