The mechanics in our Medina store see a lot of bicycle tires flattened by thorns on the Reagan Park mountain bike trails -- so much so that they have a "Thorn of the Week" award for the nastiest stabbers they pull from a tire.
And so much so that they are big proponents of Stan's No Tubes Tire Sealant ($3.99), which will stop slow leaks and seal small punctures. It will also seal punctures inflicted by aforementioned bike mechanics, as you will see in this demonstration by Don Barnett:
Medina staffer Ed Meyer recently went to change his tires after a season of riding and found SIX thorns in his old tires, which had never gone flat, having been successfuly sealed by Stan's (hence the phrase "to Stan's a tire").
To use Stan's, you need either a tubeless-ready rim or the complete Stan's kit to make your rim tubeless-ready, which includes special rim tape and a rubber liner. Stan's is ideal for mountain bike and cyclocross tires, which operate at a lower pressure. If you want to try Stan's for your road bike, you will definitely need tubeless wheels and tires because of the higher tire pressures.
Ask your Century Cycles mechanic about Stan's the next time you're in -- and avoid having the next Thorn of the Week ruin your ride.