Shelters and posters are your best bets. Lots of posters, on telephone polls, at the local grocery store, gym, etc. I'd say forget the 'net, too low percentage. If a little old lady down the road found her, she may see a poster, she may take her to the pound, but she won't be on the net.
Local kids are also a good resource. Offer a reward, amount can be unspecified if you like, but put "REWARD" on the posters.
Actually go to the shelter(s) -don't just call and trust that the person you talk to will see your dog as you describe her and let you know if she's there or not. Go see for yourself.
Good luck.