OK, new thread time... I watched my tape of "Shins of the Father" (4E08) this morning, and I just thought of something that could easily make a KotH FAQ, for whoever wants to set one up.
Cotton took Bobby to the bar on Angie Dickinson's birthday which, according to the World Almanac, is September 30. This was the day after Bobby's birthday party, assuming that the party took place on his birthday. Now, the episode probably took place in 1996, and not 1997, since September 29, 1996, fell on a Sunday and it is very unlikely that a birthday party would take place during the week. Thus, Bobby was born on September 29, 1984.
(Of course, if KotH takes the Simpsons' route and decides not to age the characters, Bobby's going to be 12 for the rest of his life.)
--Jason