Maybe I have bad Sharpie karma, but my keychain mini-sharpies tend to fall off and get lost, and my retractable Sharpies dry out. Regular Sharpies always get loaned out and never returned, but I love Libby's idea of attaching a Sharpie to your belt with tie line around the cap... this way, if I let someone borrow it, they'll HAVE to return it (or keep it without the cap)!