I really think this is a great niche. I do some contract work (when not working on my startup :)) and I can remember creating my first proposal from scratch and being somewhat overwhelmed. Not because anything in particular was all that difficult, just that there were lots of details that needed to get right, and then it needed to be formatted and professional looking. The second proposal was a million times easier b/c I had the first as a reference.

Some constructive criticism based on my first visit to the site:

- I really wanted to see an example final proposal, right away. I never did find one. I guess you have to sign up to see one? That seems like expecting too much from someone who doesn't know if they want to use your service yet.

- I didn't get what the 'negotiation' features where about. The site mentions the ability to get parts of the proposal approved or discussed with a client, but I think you need to describe that a bit more up front. I'm hesistant to ask a client to do very much work to give me a contract, so I'd need to know exactly what the client would need to do to use that feature. Sure, I could figure it out by signing up and playing with that feature, but I'd rather you just tell me. (As your potential customer, I don't want to have to do very much work to decide if I want to give you money :))