I've been using the Schwalbe "cloth" rim tape for the last couple years. It's super thin nylon material...light, tough, and comes in both 15mm and 19mm.
I just keep a roll of the 15 around and have used it on both regular and 23mm rims without issue:
http://www.amazon.com/Schwalbe-Bicyc...walbe+rim+tape
-Mark in St. Louis