Well, I'm not the person who advertises for others.
But I am looking for a longer time for my own cloud.
That means: I dont trust dropbox and other cloudsystems, because you don´t know what is going on with your files in future.
Now I found a cool programm called: http://owncloud.org/
I really like it. It is not 100% perfect at this time. Maybe you should wait for a BUGfix version of 3.0
But you can see how it is working and what you can do with php software.
All files are stored on your own server. Thats the way I prefer.
Here is the GIT version: http://gitorious.org/owncloud