Half of onion sites were hosted on FH. The list you want to compile will be very long, as you found out from the 219 addresses someone else compiled. As an indication of the size of FH, I got a new account a few weeks ago, and all of the MySQL databases I created were prepended with a number in the 5000s. Assuming these numbers are added sequentially, there were over 5000 FH accounts -- and the number of daily hits itha received was probably only rivaled by SR. What really sucks is they had just launched Onion Bank, which looked promising as an independent payment service (think of it as the anonymous PayPal of onionland), and now that appears to be scuttled. Also, they had a maintenance page up on Saturday, but now they are completely down again. That doesn't look good.