Speed Download has little to do with file sharing in the search-and-download sense; instead it is more of a hybrid application that combines Mac OS X's download manager, an FTP loader and a simple filing tool in one.
You can share files peer-to-peer, but you need to configure how this is done, and with whom you want to share them, unlike the simple dragnet searching style used by some other P2P file sharers.
Once you have installed Speed Download, when you subsequently click on any file to download, instead of OS X's download manager panel popping up, Speed Download takes over and manages the action.
The download doesn't magically transfer any faster than before through any coding wizardry, and data transfers are still limited by available bandwidth among other things. However, there is some speed to be gained when it comes to handling the downloaded file.
For example, you can upload the recently acquired file to iDisk or an FTP server from within Speed Download; you don't have to open a separate program.
There are other things you can do without leaving the app, too. There's an easy filing system, not unlike a Finder window, in the left-hand panel for dragging and dropping completed files. And you can download whole FTP sub-directories at a time, not just single files. You can even schedule downloads to take place by entering the website's URL and setting the desired download time.
Yazsoft has added a simple plug-in that links to Transmission, the popular, free BitTorrent app, so you could use Speed Download as a file manager for Transmission searches if you like.
Speed Download brings a lot of organisational strength to downloading files, goes way beyond Mac OS X's download manager, and is a snip at £14. James Ellerbeck