The biggest file I've ever seen is sponsored by Windows 7 bug :). To reconstruct the file split in WinZIP for example iso image (my has 7 GB), and then try to open it with windows explorer.
As you can see below I have one iso file and splited winzip archives
when I open this archive with winzip, I can see current content:
but in windows explorer file looks like this:
and when you try to unpack it it show funny thing :)
to be exact I have to add that file has been made with WinZIP run with legacy compression option enabled!