Beatrice Robertson mentioned patent documents (010825 MMDigest).
Another service that I've used in the past is the PatentWeb services
at http://www.micropat.com/ .  In addition to excellent document
copies (which I prefer to receive as high-resolution PDF documents),
they also provide full-text search capabilities of United States (US)
patents from 1836 to date.  Granted, the search service is rather
expensive ($95 per 24-hour day, or $495 by annual subscription),
but where else can you search on-line back to 1836?

Todd Augsburger - Roller Organs
http://www.bright.net/~allmax/index.htm