Would you consider implementing the BTC-E API into your site? That would allow us to directly or automatically sell our altcoins at the market value, or set our own prices and sell them at those prices as they are generated. Could be done if you implement a limit of 1 coin of whatever currency before your sell order goes live, and sell order can only be increased by 1 coin intervals.
That'd be a rather large project that I don't have time for at the moment.. If someone is willing to implement it in PHP I would consider adding it.
I'm about 75% done the back-end of a stand-alone auto-sell service. In Ruby. The only obstacle I'm facing is transaction fees. Transfer 1 brand-new LTC and it takes a 10% fee! I'd probably just set a 10 coin threshold, otherwise it'd take a ton of confirms to eliminate the transfer fee. I hope at the pool, the transaction fees for those taking low-threshold payouts is applied to them alone and not shared across the pool...
The fact the exchanges don't (from what I can see) offer a withdraw API (for the sold BTC) adds a bit extra risk to the equation too. I'd be giving out my local BTC, and manually refilling from the account.
Maybe the simplest would be to just let have users enter their API and private keys (of a new account only used for this), and they send their mining payouts directly to the exchange, and the service just executes the auto-sells. They can then withdraw their BTC at their leisure.
