Manufactuered by an Australian company called Hollie and Harrie, these beach tents seem like a great alternative to a beach umbrella. For one, they would be much less awkward to store and you wouldn't have to worry about a wind kicking up and uprooting your umbrella. I also love that you can adjust the strings to change the position of the canopy as the day goes on.
Sadly, the Sombrilla is a little pricey at $150 plus whatever international shipping would cost. However, I think this could be a great DIY project: Don't you?
UPDATE: I discovered some basic instructions for how to make a very similar sun shade online on the website Trails.com. Their diagram is very similar to that of the Sombrilla!