This Vbulletin extension will let your users upload their own personal smile emoticons. Users will be given their own personal space to upload their smilies and they will appear in their smiley set.
Administrators can define what user groups can add smilies. The administrator can also define how many images users can upload, the maximum file size of the images, and specify height and width restrictions. No source code edits in this extension, it is all done with product files and uploads.
Download here.