Check out how cool this is: To send a fax, just open your Google Docs document, then click the "Fax This" bookmarklet (which you can add to any browser). Type or paste in the fax number and presto: the document gets delivered. In my tests, it took just a few minutes for outbound faxes to arrive.
You can also configure InterFax so that inbound faxes land in your Google Docs account, where you can view and/or share them. The service effectively acts as a fax server for Docs.
If you want to give InterFax a test-drive, you can do so for free for 14 days. After the trial period expires, you'll have to pony up for a prepaid faxing plan. These start at $10 for roughly 90 pages (or $0.11 per page). If you want to receive faxes (via an assigned toll-free number), you'll need a monthly subscription, which is $12.95.
Those prices are pretty competitive, and I know of no other service that lets you fax directly from Google Docs. If you're looking to make your business more paperless, or just boost your fax productivity, this is definitely worth a look.
More on BNET: