IcingDragon; "Force Feeding Plots"
Michelle "A Players Guide to DMing"
Jason "Evil Party Cohesion"
Jason "Labor of Love"
Sean "Challenging the Superparty"
Sean "Plot Threads"
Sean "Secret Societies"

This is gonna be a short one so think about it long and hard. Take Notes and keep them. This allows you to use plot threads and keep them around for later games. If the characters meet a mysterious rogue in a town who gives them a helpful peice of information, what's to say the rogue will avoid the party. The rogue may follow the party's progress, for good or for ill. If they meet someone who was from a temple which was Destroyed in flames until if fell to ruin the party may find themselves in that region again some day. You can dangle things in front of the party which have nothing to do with the main plot, but in the future, when you begin to run out of ideas, you can consult your notes and remember some of the things you threw in to make a scene more colorful or descriptive. Watch the parties eyes grow in amazement as something out of their past that they barely remember suddenly comes flying into the present. This keeps the game alive, and lets the party know that they are in a static, changing world, which is possibly affected by gods, fate, chance, luck or society. It also makes a great story later. So be very descriptive as often as possible so that you'll have plenty to draw from later.