In my experience they had quite a few jobs that were not advertised on Search and/or TIE. Definitely worth subscribing.

Can someone recommend a teacher certification program that could be done by distance?

I interviewed with them and they offered me a position but I turned it down because I was offered another job in China with a much better pay. There are few very good things about this school: they do IB, have a lot of tech resources, housing, etc. They do seem a bit cheap - they pay you your summer salary in September when you return the second year, and do not pay it at all in the end of 2nd year if you decide no to renew. As for multiple openings they are expanding.