I would like to be able to specify inclusion and exclusion masks with regular expressions.
I have several multipart rar archives, which in some cases make up most of the contents of a disk. Since compressed files are best left without defragmenting, I would like to exclude all files with extension .rar, .r00, .r01 ... .r99. Same goes with .s00, ..., .s99. Simple regexps such as .r[0-9][0-9] or .s[0-9][0-9] would do, but UltraDefrag just understands simple wildcards. Of course, .r?? and *.s?? would match way too many files.
I think we don't need full fledged regexp with backsubstitution etc. For this particular case, only character classes are necessary (expressions such as [a-z] or [0-9]).