1. Give your driveway a good sweep once a month, sooner if needs be. Use a stiff bristled broom (your kitchen broom might not cut it this time.) and use short brisk strokes.
2. Wash concrete driveways with a solution of water and washing soda. Dissolve 1 cup of Arm and Hammer Washing Soda in a bucket of warm water (paint stir sticks work great for stirring until it's all dissolved). Apply to the driveway with a long handled brush/stiff push broom. Scrub well and rinse with water.
3. Oven Cleaner works really well for those stains that couldn't possibly ever come out. As it's a miracle worker on many other products around the home, the driveway is no exception. Spray it on and allow to sit for a few hours. No scrubbing required, just rinse well. This one isn't as eco-friendly as others, so make sure to keep pets and children away from the area while treating and rinsing.
4. For old marks and "mystery splotches" apply a heavy layer (no skimping) of whatever laundry stain remover product you have on hand (Zout is our own little miracle worker). Allow the stain remover to sit for 5 minutes before sprinkling with powdered laundry detergent. Apply a small amount of water to create a lather and scrub with your handy dandy push broom until gone. Rinse well. If you don't happen to have powdered laundry soap on hand, free samples can be found all over the internet with a quick google. Obviously this won't help you out in an immediate situation, but if you are planning ahead it might save you a few pennies.
5. Kitty Litter is great at absorbing oil (as most of probably already know). Just make sure to grind it into the stain with your feet. This trick is best used on newer fresh stains and with a little bit of force (putting a board over the kitty litter while you practicing your surfing helps to grind it into the stain).
6. Patio Blocks can be cleaned with the washing soda mixture mentioned previously, or with laundry stain remover. Don't use the oven cleaner method however, it will cause the color to be removed and could possibly damage the blocks.
7. Kill weeds that are growing in the cracks by dissolving 1/4 cup of salt into 1 gallon of boiling water.
8. Prevent them from growing back by sprinkling salt (table or kosher) directly onto the cracks and crevices. Do not use rock salt for this task or else it could cause the driveway to chip! No grinding in is needed, just let nature take over from here.