OK i was looking for some info about orings at work and stumbled accross this.
before you go there be warned it is literally a 292 page pdf BOOK about o-ring design and materials. to go with the book i also found the complete list of dash numbers for o-rings with their standard and metric actual sizes.
and one more this has most of the information you will ever need in one place (standard sizes, metric, gland design, temp ratings, chem compatibility)
If your looking to buy orings try these places.