I have had a Progressive Suspension Tubeless Roadside tire repair kit sitting in my underseat for a while now. It comes with cement glue, tire plugs, CO2 cartridges and a CO2 adapter hose all contained in a small box.

I had to use it over the weekend, the two CO2 cartridges nearly filled the back tire up to a ridable pressure. Worked like a charm rather us getting stuck in the middle of nowhere on Sunday, we were able to ride to a gas station fill the tire up properly and be off on our way. I highly suggest having one of these portable kits around for when you go riding.