I've use two of the download managers currently on the market for OS X and they are both a lifesaver if you have a poor connection and want to download large files. Not only are they faster than a browser — they open multiple connections to the server which browser don't* — but they resume incomplete downloads so they cope much much better with poor and failing connections.
They are ... how can I put this ... very similar. You could think they were different skins of the same product. iGetter shows the fact that it's 10 years old (which is about how long it's been saving my bacon), Folx looks more modern. They have different approaches to nagging non-purchasers: Folx distinguishes their free/pro versions, and requires a key-press to start a download. iGetter makes you wait for an increasing time when you launch the program.
They're both downloadable for free trial or purchase.
|iGetter from Presenta Software||£18.27|
|Folx from Eltima Software||£13.95|
|Folx family pack||£27.95|
* Because major browsers respect the internet standard which says client applications should not open more than 2 connections to a server.