The Nealey kits are the best:
Nealey Tire Repair Kit
The "Mini" kit will work on any motorcycle or car tire.
They're a little different than the standard sticky string:
- No glue needed
- They come in a very handy compact plastic tube complete with inserting tool.
- The only other tool needed is a knife, wire cutters, or scissors to cut the cord once inserted.
- The insertion method is a bit different -- you end up basically tying a knot inside the tire. The repair can't come out.
- The first kit I bought is about five years old, and the repairs are still soft and sticky. High quality stuff.
- The insertion tool is not a reamer or rasp that injures the tire further
And yeah, I agree -- a pump is the only way to go. You need a LOT of CO2 carts to fill a tire to a rideable pressure, and once you run out of cartridges (if you have a leak or a second puncture), you're pretty much screwed.