I was thinking of creating a free classifieds site where users could post items they have for sale, etc. Then I would just charge for advertising banner ads, etc. But, I'm wondering how I can protect myself from not being able to verify ads are legitimate. For example, would I be liable if someone posts a phony job ad for in a company's name but the company doesn't know anything about it? Are there ways around this? Even if I did a check on every classifieds ad before it was added to the site, I still couldn't verify if it was real or not.
Well, if you just put a disclaimer there you should be okay. Just make sure you post that you are not liable for the accuracy of any of the ads, that you were not the original creater of the content. I'm sure you can find a lot of examples around the web if you look. Message boards have the same liability... someone could easily post derrogatory information in a message board or forum (like SitePoint). If you're really worried talk to an attorney (probably good advice anyway).
Just be sure the disclaimer is very visible, with at least a line or two on all the actual listings (and not just in some tos that takes 2 clicks to get to). Also be sure and investigate any claims of fraud immediately and with written documentation -- that alone makes it rather clear that your intentions are good, which does count. And as beley said, talk to an attorney, only they can really tell you what's necessary.