We've had some great competitions with other schools and individuals this year using the quozr webs.

Super easy to set up, even if you are in a different time zone.

Here's a simple example,

We had 4 schools, all international and in 3 different countries.
Each student taking part had 1 hour to submit their site.
We can see by the last saved date stamp whether or not they went over. time.
I staggered the delivery of the task depending on their time zone, so each student had the exact same time to code up.

The task was to build a simple 1 page website about any sport.
Marks were given for html code, css and any javascript used and as well as content..

At a set time after the last school finished - All the sites were set public and shared on a hidden forum - so everyone could see the work of all the students.

Marks were tallied and the best school won. Special mentions were given for individual creativity and good coding skills.