1) Static website host
2) Synchronize applications
There are two ways to keep some of your apps synced. One is just putting the config-files, chatlogs, etc in Dropbox.
You can even synch your game saves! Some even support it out of the box, like Broken Sword for the iPhone.
The other way is using packaged apps for USB sticks (PortableApps), and putting the whole app in Dropbox. Personally I keep a copy of FileZilla with my sites in case I need to access one of my FTP’s. Others keep password apps like KeePass. I’ve tried having a browser synced, but noticed that the tabs I have open on one computer (work) isn’t what I want to see on another (home). Notepad++ with custom settings works great too.
3) Source control repository
Quite simply you can put a repository in Dropbox, in a shared folder with your team. It’ll work like a hosted repository and you’ll get free redundancy. The downside is that it doesn’t handle simultaneous checkins very well as it’s synching between computers.
4) Wireless transfer files to mobile devices
The Dropbox iPhone app can send files to apps that are registered for the file extension. So any .epub will prompt to send it to iBooks, which I use a lot on my iPad. The same with PDF and other files. I’m not a big fan of iTunes and I’m an even lesser fan of cables, so just putting a file in Dropbox and opening it in my iDevice is perfect. Most publishers will give you several filetypes if you buy an ebook directly from them. O’Reilly have good deals that include ePub, Mobi, PDF, APK and Daisyj, which is great since Microsoft Press works with them. Here’s a good tutorial.