Droplr was updated earlier in the week to include a cosmetic redesign, some improvements and critically a long-awaited iPad app. Droplr is a simple file sharing utility; you upload a file to Droplr and are provided with a short link that you can use to share that file with whoever you choose. I use it fairly regularly, and it's great for posting links to items via twitter or ADN, allowing you to maintain control of that item which may or may not be of benefit. It can also be used simply to link-shorten - something I tend to do if I'm texting or iMessaging a link that would otherwise be unsightly.
I think it's worth checking out if you're not already a user. Droplr has apps for Windows, Mac, and iOS and built in API support for a number of third party apps.