I love the ideas you've mentioned (openers, charms, and decorative bottle stoppers). There are a number of wonderful things out there for wine and many can be as elegant, fun, or practical as you want.
For a practical gift, I love flexible pour discs since they provide an even, spill-proof pour every time. They are also disposable so you can change them out for different varities. I also love the bottle stoppers- there is no end to what designs you can find! (These can fit into the fun category too!) You can really get creative with the gifts, especially for a girl's night out party, or fun gathering- there are all sorts of innovative products like wine coasters shaped like slippers or flip flops, wine bottle coverings that look like little outfits, etc. For more elegant affairs, you can always use organza, brocade, or velvet wine bags to hold a fabulous bottle of wine. It's also always great to give a wine-tasting set as well- with numbered wine bags, bottle signs, and/or cheese signs.