I’m relatively new to sewing, and I am wondering if there is any way to track down specific fabric designs or themes from any sort of database (perhaps online?). I travel a lot and often browse outdoor markets and vintage shops and see interesting fabrics that I’d like to have access to!

There are some shops that group fabrics by major color or pattern type or motif. http://www.equilter.com is a good example… look in the cotton prints section. The bad news is most of these are "quilt cottons" or home dec fabrics.

The other bad news is that most fashion prints are in print for only a season or two. Buy it or it’s gone, and your only other hopes will be shops with stale stock, ebay and similar secondary resellers.

If you can find the maker’s name on a selvage, and perhaps even a pattern name or number, you can sometimes go back to the manufacturer’s website and get some hints. http://featheredfibers.wordpress.com/2009/02/22/selvage-quilt-wip-mini-tutorial/ Or just do a google search for the maker name and pattern. e.g.: http://www.rjrfabrics.com/fabrics/request_fabric.cfm

The other good news is that there are thousands and thousands of new prints every year. The bad news is that some motifs go out of style and you won’t see them again for 10-20 years. Paisley is an excellent example.

And this is why those of us who sew have stashes. Pardon me, "resource centers". <g>