I just carry "basic size" safety pins - the size they give you for race bibs when you run. I used pins once when I pulled away the corner of a jersey pocket from a shirt (maybe the pocket was overstuffed), or I thought they would be handy if I somehow managed to have a problem with a full length jersey zipper. Once we used them for temporary repair of a friends saddle bag strap (it attached with Velcro vs. clips) and kept pulling open. Used the zip ties on another friend's saddle bag when the strap broke so it wouldn't be bobbing up and down while she rode. If your shoes have laces instead of buckle or Velcro closures, a zip tie could also be used to fasten your shoe if the lace broke. Marni mentioned duct tape - definitely would be useful.