Or you can just replace your toilet with one of the new low-flow, superflush models. Gone are the days of the low-flow toilets Hank Hill campaigned against. We've replaced both of the toilets in our house with toilets that use about 1.3 gallons a flush (the dual-flush uses 1.1 gallons for liquids, 1.6 for solids). The powerful flush really makes a huge difference.
Here is the toilet I installed in the upstairs bathroom:
Sterling Plumbing Stinson 2-Piece High-Efficiency Elongated Toilet in White - 404702-0 at The Home Depot
And here is the dual-flush toilet we had installed by a plumber in the downstairs bathroom (due to difficulties with the old flange):
Glacier Bay Elongated Dual Flush High Efficiency 1.1/1.6 GPF All-in-One Toilet - N2316 at The Home Depot