accumulation - Total elements of a list that have a common first element

Possible Duplicate:

List-operations only when restrictions are fulfilled (Part 1)

I have a set of data like:

list = {{Tim, 45},{Mary,100},{Tim,500},{Bob,499},{Mary,50}};

I'm looking for a simple way to total the values based off of the name so that the output would look like: {{Tim,545},{Mary,150},{Bob,499}}