I'm after a pretty specific colour for my rim stripes and these guys seem to have them all. They'll even do custom length and width for a small set up fee.

Flat colour
Fluorescent
Reflective
Metallic
Pearlescent

Select your brand of bike and see their swatches for a 'best' match.

Check 'em out.
Tapeworks Rimstripes Homepage

Edit: Oh crap, DUBS has done it.... as you were.