Say What? OCRing TIFF files?
This is news to me. SharePoint - is there anything that it can't do?
How to customize SharePoint Portal Server 2003 or Office SharePoint Server 2007 by using IFilters, noise word files, and thesaurus files
update: unfortunately, this doesn't work on MOSS 2007.
You should check out the largest source for OCR online: www.ocrworld.com