The only thing I have ever used is ineedhits. I just use the cheap 2 buck submission service – they do do it by hand and for 2 bucks I save myself the time. They also manage various paid guaranteed inclusion sites that do accept gambling – but you are best off making double sure before you pay.
I have used them for years and they do well. Just don’t buy any of the repeat submissions or traffic or whatever extras. Stick with the cheap basic service and if you want guaranteed inclusions, they work well but like I said, doublecheck about gambling sites.