Hi All,
Most of the posts on this thread have mentioned FFEDITc_unicode.exe. This program is also used by Shape File Manager, but the main problem is that FFEDIT is part of MSTS which is not (as far as I am aware) available separately. As it's getting more and more difficult to purchase the MSTS CDs, these suggestions won't be applicable to many users.

Archibald (part of tk_utils.zip) has also been mentioned; this allows direct editing of .s, .t and .w files, among others.

Also available from the file library is recmp119.zip which contains two utilities, comp.exe and decomp.exe. These allow the compression and decompression, respectively, of .s, .t and .w files, but they take longer to do so than FFEDITc_unicode.exe and should be used with care because by default (I believe) they overwrite the source file. I used them in my UKFS_Fix utility, so do speak from some experience!!