At first glance, Owncloud is a free and open source alternative to Dropbox. As their site reads, it is "your data on your servers, under your control." It works just the same as Dropbox where things are kept in constant sync and you can undelete items with versioning. It's a nice middle ground of universal availability, but owning and controlling your own data. There are clients for Mac, Windows and iOS. In my testing of Owncloud 5, the syncing is even quicker and more stable. Check out all the features here.

If you look a little futher, you'll see that it even does more than syncing. You can also sync address books, calendars, and bookmarks. There are also a number of apps you can install to add more features including tasks, notes, etc. Soon, there will also be a great ownCloud alternative to Google Reader.

As you would guess, Owncloud works great on a Mac mini. Here is a tutorial for installing Owncloud on a Mac mini. I was going to post screenshots and a walk through, but you can try a demo of Owncloud right online.  And if you like it, you can download from their site. 

If you have any questions, you can reach us @macminicolo on Twitter.