When you hit the cyclocross races, a pint of tire sealant is a must-have in the pits. You can use a bit of sealant to make emergency repairs to punctured tubulars or tubeless tires.
This injector from Caffelatex allows you to insert sealant right through the valve core - in many cases you can repair your tubular without removing it from the rim, or your tubeless tire without breaking the bead. That's a big time saver and could save your race results.
You can also add sealant as a preventative (for example, before racing/training on a course with the dreaded goat-head thorns).
This works with standard presta valves, presta valves with removable cores, and schrader valves. A handy gauge on the clear body allows you to measure exactly how much sealant you are adding. It is recommended for use with Caffelatex sealant, but should work just fine with Stan's NoTubes, Slime, and other sealant brands.