do anything and everything that can get your work seen. but don't spam; bring up your work subtley or in appropriate situations. some ideas:

-online stuff: tribes, blogs, mailing lists, signature files, your website or profile. mention your product and how to get it everywhere appropriate.
-business cards, stickers, other stuff with your business name, url, etc: include them with everything you sell, give them to everyone you meet who you think might be interested, put them in with the packages of stuff you sell
-display your art on a regular basis: make pins out of your cards and stick them on your jacket or bag, put stuff up at your house, ask about displaying your art in local businesses you frequent (like cafes)
-create reasons for people to see you as an artist: host a workshop teaching people techniques for making ACEOs, volunteer to help kids do crafts--their parents may ask about what other art you do, get interviewed by a local paper
-craft fairs, holiday bizarres, local craft shops, concerts, festivals, and other offline places may be good venues to sell from
-make t-shirts featuring your art. get all your friends to wear them.
-sell your stuff in innovative ways: sets of cards, grab bag assortments, turn them into a deck of playing cards...

be creative with your marketing just as you are with your art. everything I've read and experienced about selling goods or services tells me that visiblity to your market is important. since I started being more out there with advertising my services (I don't sell goods, yet), I've gotten a lot more new business. And repeat business, actually. Reminding people I've already sold to is even more lucrative than getting in new ones, but most businesses have to do both.

Yeah, all on ebay, I had tried the artcardauctions.org or whatever it was, and not only no bids, but no one even really looked at them.

I'm still not getting as much traffic or as many bids as I would like, but I really don't know what else to do about it but keep putting more up.