Nope, no way to combine Disney Gift Cards.
However, if you're staying at a WDW resort, you CAN put all those cards down as a deposit to enable room charging on your KTTW card, thus letting you carry only one card around the parks with you.
NOTE: Not all check in CMs know that you can use cash, Disney Dollars, Disney Gift Cards, or travellers checks to enable room charging, and some may tell you flat out that it can't be done - that you must use a credit card - but this is not true. I use Gift Cards and Disney Dollars to enable room charging all the time; if you get a CM who doesn't know how, just politely request to speak to a supervisor. All supervisors know how to do it.
How did you get so many gift cards to begin with? Some kind of rewards program?