I just got a new prepaid broadband 4G wireless plan via T-Mobile. They have caps on data usage; you purchase what you think you'll need for a 30 day period. There are no overage charges, but when you run out, you run out. The service does not continue at reduced speeds like some plans. I wasn't sure how long I'd be able to go with this plan, but by chance I was listening to Clark Howard, the savings guy on HLN who mentioned that the free Opera Browser greatly reduces data usage via the Turbo function and the easy no pictures option on the tool bar. Opera is good for slow connections too. I think it works by filtering the website information through their proxy servers, and then it is sent to you in a split second in a smaller file. I've been using it, and it really has saved me data. Apparently it's the defacto browser choice for Smartphones and other mobile devices.
If you want to extend your browsing when limited by broadband usage caps, Opera is the way to go.