craftgrrl | Advice Please: Marking on fabric (Reply)

What's the best way to permanently mark fabric?

I know embroidering would be ideal but my skills are lacking and I want the marks to look nice as well as last.

Here's what I'm up to. I want to re-use the t-shirts I get from running 5Ks (maybe make little pillows or a patchwork blanket) BUT I want to note my time on each patch. The item would be laundered (not a ton, but some). The patches might not be super large (just the front of the shirt, where the name of the race/decal is) so space is at a premium. I'm not adverse to the idea of iron on/patch type lettering but it needs to be something that will stay nice looking.

I'm also open to advice on working with t-shirt material (I haven't started the project yet, so words of wisdom/warning are very welcome).

Thanks!