I've been mulling something over and thought it worth tossing out to see what the trend in feedback might be. Some time back Dan assisted in getting some data added to each Classifieds posting that showed how many previous ads a user had submitted. Truthfully, this information only goes back a few years, but I think is very, very useful in establishing trust with your seller. It's letting you know if you're working with someone that has a history here. Having a history (99.9% of the time) means the participation has been free of things that tend to get a seller or buyer booted (not delivering an instrument paid for, non-payment when seller sent before received payment, other fraudulent activity, etc.). What I often see is what may look like an ad that's a bit suspicious, I dig around and find the individual has a history going back several years of replying to ads, but has never placed one. Same rule applies. The fact they're participating means they're good folks to deal with, and really, 99.99% of them are great folks to deal with. It's the remaining few I deal with and evaluate on a daily basis.
I'm considering having the number of replies displayed next to the number of ads. I think this is really useful information. So, Joe Blow, this is his first ad he's ever placed, but he's replied to 29 ads. That paints a very different history that what we currently offer. I can understand someone possibly saying, "oh, that's invasive," and you're welcome to that opinion. I just don't agree with it.
Bottom line: fraud is not going away. You may think that having systems protected by credit cards and logins improves security. Case in point: eBay, Craig's List. I see this as another step in identifying people who participate here over the long haul. There are a lot of them and this data could be a further step in painting a more complete picture of the individual you're dealing with.