Harris Cyclery has a 13-30 custom Shimano cassette that might be of use. I've run a mountain rear DR with the 30 tooth (LX or XT). However a medium range such as an Ultega GS triple will supposedly operate properly even though the published max is 27 tooth.

http://sheldonbrown.com/harris/k7.html

A swap of the rear cassette is the simple way to add some climbing gears. And its easy enough to go on up to a 32 tooth rear with the addition of a mountain rear DR.

Alternatively, I recently had a Deore M532 Hollowtech II trekking (48/36/26) crank set installed on a commuter bike for my son and it is a great buy. But if you have a road group front DR (105, Ultegra, etc) you may have front DR issues with the smaller radius rings, particularly if you drop to a 24 tooth small chainrings.

My recommendation: Casette changes and possible rear DR change if you go to a 32 tooth rear. Cheap, easy to reverse, easy to work with brifters.