It's been very wet lately, and riding in rainy weather can really make you want to stay inside. You may have fenders on your bike, but do they really do as good a job as they could. Also even if you stay relatively dry, you still have all that mud and gunk gumming up your drivetrain which — trust me — can get very expensive, since all that dirt accelerates wear.
The solution is simple: buy some mud flaps for those fenders. Alright, this is Cycling on the Cheap, and before I get lots of complaints about my promoting consumerism, let's explore alternatives. We could steal them or just build our own. I think we will go with the latter, as bail is not cheap either.
For materials, you can use pretty much anything but most are made of rubber, plastic, metal or leather.
The best web site for looking at do-it-yourself mud flaps is Alex Wetmore's site (any man who was linked by the late Sheldon Brown is worth looking at).
Those who do not have a problem with using leather can see the following sites:
which feature step by step directions on creating leather mud flaps. I think that the material is secondary to the design of the mud flap, so I am sure you could substitute leather for just about any material.
And if it is still raining and fenders and mudflaps are not enough, then you can always try to make your own waterproof booties.
Be sure to grab a third sack for seat because nothing is worse than heading to your bike after a rain and soaking yourself on a wet seat.