It's easy enough to write off TransferBigFiles as just another cloud-based file transfer service with an iPhone app like Box or YouSendIt. However, TBF claims its app is the first to let you send full-quality HD video files created with the iPhone directly from the device over Wi-Fi or 3G--no need to sync, convert, or connect to a computer first.
The app is pretty straightforward. You can create a free account through the app or with the company's Web service, sign in, and start uploading and sending. The input box for adding recipients isn't linked to your contacts, so you'll have to input e-mail addresses on your own, which is a pain. But otherwise the process is effortless and if you're uploading a large file, the app will run in the background for up to 10 minutes on iOS 4. Also, should you drop your signal or interrupt the transfer some other way, the upload will resume where it left off.
The Web service has free and paid account types, which apply to the app as well. Signing up for a free account gets you 2GB of online storage for iPhone files, but the first 100,000 users to install and activate the TransferBigFiles iPhone app will get 5GB for their video and photo uploads. Even if you never buy into the Web service, that's a good deal for occasionally sending clips off to friends and family or for business.
Update: Just to clarify, the iPhone transfer storage and Web service storage are separate amounts. While the free account gets you 2GB of iPhone transfer storage, it only includes 250MB of Web service storage. The free account is nice for sending off a video clip or photo, but you'll have to buy into the Web service to make that worthwhile.