First of all, I am bit sceptic and unsure of how you are making the money out of an OS project. In case you are building something upon the OS code, then its fine to sell it as a service or product and you deserve to earn the profit.
But, if you are just making the money out of the OS code only, then it's illegal, so be aware
Other thing is that people contribute in a opensource project not for money but making good code freely available to all for reuse accordingly. If they had been working for money, they would have never contributed. Just make sure that OS project lives longer and grows to help one and all
BTW some of the contributors might be making a better product of the OS code and earning themselves.
UPDATE : Sorry i forgot to tell, there is no such service as you asked for. If there had been, there would been no OS projects as there are today :-)