I use Squid w/WebMin:
http://www.squid-cache.org/
there is a nice web based interface for Squid with WebMin:
http://www.webmin.com/
Squid, however, uses disk & memory caches. Not sure if it can be configured for only memory cache. Maybe. Let us know, Thanks!
Quote:
Squid-1.1 also uses a lot of memory to store in-transit objects. This version stores incoming objects only in memory, until the transfer is complete. At that point it decides whether or not to store the object on disk. This means that when users download large files, your memory usage will increase significantly. The squid.conf parameter maximum_object_size determines how much memory an in-transit object can consume before we mark it as uncachable. When an object is marked uncachable, there is no need to keep all of the object in memory, so the memory is freed for the part of the object which has already been written to the client. In other words, lowering maximum_object_size also lowers Squid-1.1 memory usage.