I very much enjoy buying glasses with etches that I do not recognize.  For one thing they are usually less expensive than well known patterns.  So I have bought a number of glass identification books to help me.  This set of guides are probably my favourites.  I bought one somewhere, liked it so much that I ordered the other three.  I like having the colour photos.  I find it much easier to identify patterns from colour photos than sketches, or even worse, black & white photos.

These guides offer a variety of etches, cuts, blanks from different companies and eras.  I highly recommend them.