Don't get all hung up on the knots... that's what scares off a lot of people. You don't need to know but a small handful to get the job done!
Having said that, here's a couple of RARs with all of the knot e-books I've found. The first is the Ashley Book of Knots, one of the best references that everyone refers to. It doesn't list every knot in the world, but it's got damned near all of 'em. The second RAR is only 16meg, and has an assortment of other e-books. You don't really need the second one, it's just there 'cos I had it.
[hide]edit Jan 2009: both links are dead... PM me if you want me to re-up them![/hide]
The Ashley book is a photo scan with a PDF index (bookmarks), but it's not searchable 'cos they didn't OCR the text. I have another copy that *was* OCR'd, but the lower image quality on the knots made it hard to see what was going on. Of the several copies I have, this one is the best. One of these days I need to go through it and expand the bookmarks to include all of the knot names within the sections to make it quicker to search... so many projects, so little time.
Here's what's in the second RAR:
fm5-125 Rigging Techniques.pdf
Handbook of Knots and Splices - Charles Gibson.pdf
Mastering the Art of Knots and Splices.pdf
Stagecraft Manual rev06.pdf
Surgical_Encyclopedia_of_Knots.pdf
The Klutz Book of Knots.pdf
US Army - Rappelling TC21-24.pdf
Knots, Splices and Rope Work (HTML).zip