Last time the data dump went out (April), I noticed it was quite large. And I can only guess that the next one will be much bigger. I noticed that the default LZMA compression algorithm is being used. However, 7-zip supports a compression algorithm called ppmd. This algorithm is much better at compressing text files, which is basically what the data dumps consist of. I did a little trial, with the Stack Overflow files from the April dump. Here's the numbers I came up with.
Uncompressed= 16,274,007,260 bytes LZMA compressed = 3,701,540,987 bytes PPMd compressed = 2,501,197,899 bytes
That's would give us file sizes only 67.5 % the size of using the current method being used. And since 7zip supports this format by default, all it would take to use this is to switch a single parameter when doing the compression. I'm on a limited bandwith budget with my ISP, and I'm sure others are as well, and would appreciate having smaller files.