iPhone app to download/upload files

How can I upload/download files from/on to a jailbroken iPhone 3G?

Are there any apps that allow me to do this?

Solution 1:

http://www.dropbox.com/iphoneapp

2 Gb free account. No jailbreak needed.
Uploaded files can be private or be made public (accessible via http link).

Solution 2:

Diskaid will let you manage the contents of the filesystem from your Computer.
iPhoneBrowser will as well, but the interface is much cruder. It is free, though (DiskAid is $10).
i-FunBox is another free option (though not open source). I have no experience with it.

On the iPhone, you can get SafariDownloadManager to download files. It's $5, unfortunately.

Once you've downloaded the files, it's likely you will need to move them to whatever application you want to consume them with, so a local filemanager is probably needed.

iFile is a really nice file manager, and is good for moving data files between apps (books, etc...). It's a few dollars, though.
I believe there are a few free filemanagers on cydia. I'm not familiar with them, though.