Here is a whole book of charted Celtic designs - from simple chains/cables to amazingly intricate knots and animorphic designs. The only problems that I have with this book are:
-It's all in black and white,
-The chart squares are tiny - I usually have to transfer the patterns somehow to a larger graph to follow it accurately, and
-it is just general charts, for all needlework, not specific to knitting.
In spite of those drawbacks, though, I highly recommend getting this books - the sheer volume of charted designs would keep me busy for a loooong time...
forgot to add the link - here it is:
Celtic Charted Designs
This is one of those interactive books, you can click thru the pages and check it out!