It tackles a simple problem but once you start using it you'll realize how much more convenient it can be compared to email or firing up a file sharing website to manually upload a file. Its simplicity reminds me of Dropbox. You get 1GB of free storage and can manage every file you upload with Droplr through a well-designed web interface.
The official desktop client for Droplr works only on Mac OS X, but an enterprising developer named Bruno de Carvalho has made it available for Windows users as well. WinDroplr emulates the very same usage behavior as its Mac counterpart. You will see the application lying in the system tray, and above it, a small drop box supports drag & drop behavior to begin uploading and sharing right away. Check the video above to see it in action.
Neither Droplr nor WinDroplr require you to create an account with the service. Instead they use your Twitter credentials to generate a one-time encrypted token that is used to perform the handshake with Droplr -- which makes setup even simpler but it's also a drag for those that don't have an account with the micro-blogging service. That said, creating an account on Twitter will take just a few seconds and even if you don't use it Droplr is worth a try.