I'm evaluating software that will limit the access our employees have to the internet. We're looking to block the standard sites, like pornography, Ebay, etc. I'd appreciate any words of wisdom on different applications and companies.
The answer to this question depends on what services you wish to allow/disallow/filter and to what level of granularity you need to control it.
In your post you reference web browsing (HTTP) and specifically content request filtering (rules like disallow web requests to *.ebay.com etc.). In this specific case implementing an http proxy server in concert with some routing or firewall configuration will allow you to enforce this type of policy.
In order to effectively choose a solution, or in most cases solutions, you will need to outline an AUP (acceptible use policy) for your company that details the rules as it applies to all users, as well as exceptions to those rules. It should attempt to include all communication systems and protocols as well.
