Vuvuzela 2010 has a simple interface: a long vuvuzela fills your screen lengthwise, and you just tap it (or, even better, shake your device) to produce a loud, realistic "vuvu" drone, which sounds even better on speakers or headphones.
You can tap (or shake) it repeatedly to create a looping--and potentially even more irritating--sound, and you can customize the horn's color by tapping one of 10 jerseys flanking the vuvu on either side of the screen, with popular color combinations such as Brazil's green and yellow and Holland's orange and black.
Whether you're hoping to amuse or annoy your friends--or just cheer on your team--Vuvuzela 2010 is a well-built app that provides a good bit of fun for free. And for vuvu virgins, it even provides a thoughtful warning ("a vuvuzela has a very annoying sound!") the first time the app is opened.