At my day job, I write code for a company called Berkeley Data Systems. (They found me through this blog, actually. It's been a good place to work.)
Our first product is free online backup at mozy.com. Our second beta release was yesterday; the obvious problems have been fixed, so I feel reasonably good about blogging about it.
Our back end, which is the most algorithmically complex part -- as opposed to fighting-Microsoft-APIs complex, as we have to in our desktop client -- is 90% in python with one C extension for speed. We (well, they, since I wasn't at the company at that point) initially chose Python for speed of development, and it's definitely fulfilled that expectation.
(It's also lived up to its reputation for readability, in that the Python code has had 3 different developers -- in serial -- with very quick ramp-ups in each case. Python's succinctness and and one-obvious-way-to-do-it philosophy played a big part in this.)
If you try it out, please note that after the beta period (my guess: at least a month) the "price" for mozy is that every so often we'll send you advertisements by email. (But we'll never sell your address to anyone else, and we promise not to allow any body-part-enlargement crap.) We recognize that some potential users may be turned off by this, and we will probably offer for-pay options in the future, but I don't have a time frame on when that might be.