Best internet connection from multiple homes?

My wife and I both use MacBooks and live in 3 cities where we have an internet connection in each of the homes, each with a wireless router. Needless to say we can only use one of the connections at a time while the other two sit dormant but still end up paying for the full month fees for all 3.

Is there a better way to stay connected without the unnecessary duplication of separate access fees other than just to hang out at Starbucks?

Something like what cell phone companies have which is a wireless data plan for you computers.
Edit: Model broadband

I think the mobile broadband is a great idea, as long as you have good cell service in all 3 of your locations.

Be careful if you choose mobile broadband. Read the associated data plans carefully. Some providers have a cap in the amount of data that can be used without an additional fee.

I checked with Sprint in June or July of '09 and discovered their plan had a 5 GB per month cap with a fee of a few cents per kilobyte for each kilobyte. I was told that they were not currently charging the overage fee but they clearly could.