My favorite is flexRenamer - that is real live preview!!!
I think the site is in japanese and I can't find it this minute, but the program is very nice
* simple precanned actions
* can do files or folders, recursive as well
* advanced options supporting supports regular expressions, translation mapping, and normal windows style wildcard
* can use attributes as part of the rename
* can use tmetainformation for certain types of files (music tags, exif and iptc for images, html meta tags and office meta tags)
* instant preview of the effect
The last one took the cookie for me - it is instant (although tag rename can take 3-4 seconds) even on very large trees (10'000 images, say) and means you can figure out your regexp and refine etc. In one of my previous jobs this program meant that our designers were able to rename/renumber large number of images coming from clients in minutes, without having to involve the techies
Should do a mini review to show all the options
EDIT: found the link in the "about flexible renamer"
http://hp.vector.co....s/VA014830/FlexRena/