urly.de is a utility that allows users to shorten a long URL and share it on twitter.com or other services.
For example, you can turn this link:
Into this link:
urly.de can help you hiding the referer of an URL, for example use:
... and the webmaster of the destination page won't be able to see where the click came from.
First of all, your twitter account data is safe! urly.de isn't able to get your twitter account password, because the verification is done by twitter.com (via OAUTH).
If you login with your twitter account, you'll be able to send a status-message with the short URL after shorting a long URL.