you should try betcoin.ag
another way is pokerstars... freerolls almost every hour and if you want to do a deposit/withdraw using bitcoin you can use neteller.
Little off topic but can you explain how you are using neteller and bitcoin to cashin and out of Pokerstars?
I would love to go back to playing Pokerstars but I did not like using my bank account and that restricted most options.
-----------------------------------------------------------------------------------------------------------------------------------------------
Back to the topic,Nitrogen has a cheat/multi account issue that makes playing their freerolls a real pain in the ass.
You will see about 50 players and a good half the field are multi accounts. So you get your allin called by 3-4 other players in hopes they knock you out. Its not poker and you end up just sitting there hoping to make final table and luck out.
Fortunejack seems alright if you can double up early and then just call the aggro fish allins once in a well to cash.