I just recently moved to a new apartment, and I have to wait 2-3 weeks before they can setup my internet connection. That really sucks. Perhaps some of my neighbours would see the opportunity and earn a couple of bucks with his wlan router.

I will start developing it later when I have finished my current bitcoin projects. However that will take time, so be free to implement the idea 

Perhaps this could be even a profitable business, a company would offer the software/wifi routers and take a small cut from internet subscriptions.

To those that don't know, DD-WRT is an open source firmware for wifi routers, so additional functionality on top of it can be implemented easily. http://www.dd-wrt.com/site/index

Or use Electrum or Stratum protocol.

Except for the bitcoin part, thats what fon does (http://corp.fon.com/en).

Its been a while since I used it, but its free wifi if you share one, and users without a shared AP themselves can buy access for a small fee.

They have routers that users can setup to make it easy, and makes 2 ssids, so the one you let others use are seperated from your private LAN.

why isn't an option ? because it takes too much resources on the router or it could be hacked ?  bitcoind has ssl support too

I'm currently running an open wifi network on my internet connection and using "nodogsplash" to hijack the first page access to display a message

WiFidog, has a lot of functionality and allows for payment:
http://dev.wifidog.org/

This... they will either fuck with your customers connections (html injections for one example), or filter you.  Also, many connections have monthly cap.  I'm talking about in the US, on Comcast's network to be clear.  Other jurisdictions and ISPs will vary, so check the terms of use.  They will find you.  Your statistics will be very different.

If you run a linux firewall it would not be too hard, setup a tor relay and force all users to use the tor proxy, like many corporations already do (transparent proxy).

But tor is often slow and barely useful to check email.

Bitcoin?

Some of the router captive portal packages are third-party companies, the router sends the wifi user to a page on their server where they can purchase credits or a password, and the owner of the router gets a cut of the profits. Hotels outsource to companies like this, where 24 hours cost $10 or something ridiculous like that. It would seem easiest to convince these companies to take Bitcoin too, as they already have the rest done.

If someone makes a captive portal that accepts bitcoin I will install it.. 

I think this is a great idea..