UnZip operates as a powerful compression utility, but it will only work for a small number of users. This isn't an app in the traditional sense, but an add-on for the UCBrowser. If you happen to use this browser, this is a very worthwhile tool to have on hand.
You will need to have UCBrowser already installed before you add UnZip, but it's easy to add once you have the browser set up. UnZip is a great companion to the UCBrowser, fitting in perfectly with that browser's layout. It takes over from the download menu when you long press a file. By default, it will unzip your file to the same location as the original, which makes it easier to find the file once you need it. You can change the file's location when you unzip or zip it, though, which is a nice touch.
The only problem with this basic but effective app is that it only works with one browser. If you're a big fan of UCBrowser, this app is a great addition. However, if you use one of the many other popular browsers on Android, you'll probably want a standalone compression app instead of downloading a whole new browser to use this one.