I've built a few custom search engines using google, and was wondering if anyone had done the same and had much success (traffic, users, etc)? Thanks!
No, they don't have a very high success rate, unless you have built one with great graphics and incredibly user friendly or for a site that has a lot of dedicated users. If you can get users to use them and search daily, then yes they are very good for money. But sometimes it can prove hard to get people to use one rather than Google itself!