>Will we ever run out...? Let's see. 26^3 = 4056. That would seem to be the upper limit using English letters only. You can get a few more by adding characters from non-English languages. <g>
>

Minor correction, 26**3 = 17576 combinations. That gives a lot of options. :-) If we include the 10 digits then 36**3 = 46656 combinations. It ought to take a while to run out ... and then we can probably reuse old ones as they drop out of use.