My DP has the magnetic signs on his truck all sides and tailgate and has gotten calls from them, and they can be removed easily when you don't want to be "on call". My SIL has the vinyl lettering on her rear window and that works great for her biz, though it's not removable til you want to get rid of it for good. For my own biz I plan to get the magnetic car signs, and I've done flyering in neighborhoods where I stick my postcard w/scotch tape (it's windy here) to the door knob or dead bolt and have gotten clients this way and it's great exercise too. I agree the windshield flyers are not a good way to go. I helped a friend of mine mail out postcards from a list he bought I think it was about 500 and he didn't get one single call. Generally I think stuff that gets sent in the mail people easily overlook.
I too look at the ad inserts in the paper and those envelopes of coupons and ads that get sent out several times/yr as well as bulletin boards which I've also gotten clients from.
Good Luck!!
Chelsie

PS another thing you can do is talk to your local paper about doing a new biz spotlight/press release. It's free here and I think they do several/week