What about getting a nice little pottery or silver dish that she can put her wedding ring in, like a little jewelry plate. I never take my ring off and maybe she won't either, but I still like my little dishes for other rings and earrings.
Do you have Anthropologie near you...they always have fabulous stuff like this! I L. that store!
Have you been friends with her for a long time? Maybe you could get her a little gift bag of things that remind you of your life together thus far and include a note that says something like you can't wait to include her new husband on some of the fun in your lives or something. For instance if you guys usually go get your nails done, get her some nail polish. If you both L. ice cream get her a funky bowl (Target has some cute ones) and a scoop, if you often go for coffee, get a little Starbucks $5 card, etc. Put it all in a bag and it's done! It's simple, you can probably get everything at Target or someplace like that and it really is sentimental when you include a note clueing her in on the theme.