One of the ISVs I work with is Memba. Memba last year started to beta a file transfer platform to publish, share, send and transfer very large files over the Internet - Velodoc.

From that work they went on to create Velodoc XP Edition, a downgraded version of Velodoc without repository and without security which they recently released under the GPL license at http://www.codeplex.com/VelodocXP.

This is a comprehensive package containing:
1. An ASP.NET Http module to stream the upload of large files (compatible with IIS7 integrated pipeline mode);
2. An ASP.NET Http handler to provide resumable downloads of large files;
3. ASP.NET server controls to develop user interfaces with file upload functionality, including a multi-upload control, a listview control and a progress bar control;
4. A web application which is an FTP replacement for exchanging large files with email contacts and which also serves as a sample implementation of the components listed above;
5. A windows service to periodically purge old files;
6. A test project;
7. A deployment project;
8. A setup project;
9. Documentation.

Also check out the following articles on codeproject.com:

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Well done folks!!!