Thanks for the responses Lander.
You are right about the add-on possibilities. From what we have heard from sportsbooks, they like the idea for WAP devices, but are concerned about having their lines on a regular PC website due to agreements with other services. If the route to go is joining with an established service that wants to expand its capabilities then that might be the direction we go.
Your other ideas are ones we are currently working on. To start, alerts will likely be any move off the best line available for a game you choose. However, giving the user the option to pick the exact line they want to be alerted at is a goal we are shooting for as well.
Thanks again.