Octopus

Octopus is a multi-threaded download manager, which resumes interrupted downloads and enables you to open simultaneous connections to download programs and files from the Internet.
The multi-threaded feature in Octopus increases data transfer speed up to 10 times more than simple download and its resume download capability automatically re-starts a broken connection from where it was interrupted.

Octopus includes a data integrity system, which compares the last bytes of downloaded file to the remote file and retrieves any missing part.