I happened upon Rodale's Successful Quilting Library: Creative Embellishments, edited by Darra Duffy Williamson at my dayjob, and what a treat! While many of the quilts in the book aren't really my speed, there are so many fascinating tips on various embellishments - there's bound to be at least one you don't already know about. The most mind-blowing, why-didnt-I-think-of-that for me was: to attach shells without holes to your quilt, use epoxy glue to adhere it to a small shank-type button, then, when it's dry, sew it right on!
I hope you can find a copy in your local library (or even hiding among your own home library!). It's a great read.