I'd make this site more focus about apples to apples comparison within the same company. I.e 'Share your salary at X and invite your colleagues to do the same'. So people could go to honestsalary.com/company and collaborate there with the main page showing the aggregate.

And maybe instead of job title use department and 'level' to make it more ambiguous. I.e engineering,marketing,operations or 'associate, sr, manager, director, vp, cto'.

The problem with title is that with small companies title alone isn't ambiguous enough. Yeah yeah I know it's technically illegal for a company to retaliate but that is being a bit naive. Some companies will - the law is pretty toothless here and there are plenty of ways to subtly do it.

Also use HTTPS. For obvious reasons.

Otherwise i'm a fan and I was actually looking for an something similar the other day.