Mac Mini as a webserver?

A fair number of people, and even some hosting companies used even the original G4 Mac mini as a web server. It was (and is) considered perfect for locating in a data center due to its small size, low cost, and very low power consumption.

As the Intel Mac mini is significantly more powerful but still has modest power consumption and is the same minute size, pretty much all the same advantages apply.

So yes, for the amount of traffic you describe it is perfect.

It is possible to use even the 'personal websharing' feature in the 'ordinary' Mac OS X 10.4 software as the webserver since it is in reality Apache just like the full Mac OS X Server. I have even used this to run Squirrelmail (webmail) on top. Unlike the full Mac OS X Server, you will probably have to hand edit some of the Apache configuration files since it does not include the Mac OS X Server Configuration utility to do this (e.g. to turn on PHP).

I think just about every angle has already been covered except for one: the fact the Mac mini is a physically small system should not prevent you from considering it as a full-powered desktop computer, capable of pretty much everything any other desktop computer can do (and actually a fair bit more than some). It has laptop limitations in terms of lack of internal upgrade options, but with fast core 2 duo processor, a base of 1Gb RAM and a design capable of running 24/7, it is a very capable system indeed.

I have been using a G4 Mac Mini as a web server for about two years now. I have had the system mounted under a desk hosting web/email/vpn/file sharing/ftp/smb/dhcp/dns services for 5+ domains 24/7 with out a single problem. The only down time that I have had is either a server update or an ISP problem. I have even stayed up and running during a couple power outages. Even though my battery backup system is only rated for 1 hour, I have seen it keep the Mac Mini running for 2.5+ hours because of the Mini's low power requirement.

If you keep it cool and clean, it should work fine for your purpose.