This was a question that was recently asked in an internal thread regarding the list of available advanced settings in vCenter Server. You can find these settings under the "Advanced Settings" section of all places 😉 and this is available both in the vSphere Web/C# Client.
I wrote a script awhile back that allows you to modify these advanced settings and with a slight modification to the existing script, I was able to produce the complete list of available settings (available via the vSphere API) that are user configurable, as not all settings are configurable. Below, is a table of all vCenter Server 5.5 advanced settings and I also have a table for newly added advanced settings for vCenter Server 6.0.
Disclaimer: Most of these settings should be left at their default and if you do need to make a change, make it is through a recommendation by either VMware's documentation or from GSS Support as modifying some of these changes can negatively impact your environment.