Some great answers here already, and in general I agree with the strategy of focusing on just one domain where possible.

So, if you agree too, the next question is how do you come up with a new name/brand/domain to capture it all?

I've done several branding/naming projects, and my recommendation is the following:

1. Nail your positioning. This means, in very few words, how are you positioned with your target customer, and against your competition? It's not easy to simplify this down to a couple sentences, but it is imperative.
2. Find a name that speaks to, and supports the position you are taking. There must be a strong tie between the position and the name, otherwise creating messages (marketing) will be very difficult.
3. Find a domain to call home. The beauty of a highly distinctive position and related name is that finding an available domain becomes MUCH easier.

Let me know if you'd like to talk more about the positioning, this is the hardest part and good to get help on!