I just tried out a web host called Drophost. Instead of the usual ftp publishing, it uses Dropbox. It's super simple and works nicely with RapidWeaver.
Go to http://drophost.it and click the Log In button. If you've signed into to Dropbox recently it will go directly to the Dropbox authorization page and ask you to connect a special folder inside of Dropbox to the Drophost app.
Make a new Webspace
Click the "Make a new Webspace" button. This will create a new host and a new folder inside of your Dropbox folder. Each webspace has a numeric ID. (I'm using 1360 in these examples, your ID will be different.) The ID can be used to test out your website like this: http://1360.drophost.it
After Dropbox has finished syncing these new files you'll see something like this inside your dropbox:
To keep things safe Dropbox only allows Drophost to sync files inside of Drophost folder.
Publishing without FTP
In RapidWeaver choose Export Site… from the File menu. Instead of publishing this will just export into a folder on your Mac. Tell RapidWeaver to put them in the Drophost folder in 1360 numeric ID folder.
Testing it out
If the site is small, it should finish syncing in a minute or so. After the syncing is complete you can go to http://1360.drophost.it (remember to replace 1360 with the real ID of your webspace). If it hasn't finished syncing you can wait a minute or two and try again.
There's a Sync button on the Drophost website too, although I never needed to use it.
You'll probably want to set up a domain name and attach it to your site. You can buy a domain name from Drophost or use own DNS provider (Hover is great). Click the Domains button in Drophost to get the IP address you'll need.
You can even do edits (via HTML) from the Dropbox app from iOS.
At the time of this post, they're running php v5.5.9 on Apache.
What does all that mean? It means you can use Drophost that publishes form data that automatically syncs to your Mac.
From the looks of their site, I suspect Drophost is just getting going. I'm sure their infrastructure is fine for modest hosting needs, but high traffic sites should probably stick to well known providers.