Same thing on the bus I take to and from work. There's this
semi-regular rider named Dan, a slightly older gent working as a IT
manager in a large insurance firm downtown, who always sits next to me when he rides
the bus, and insists on striking up a conversation with him doing
about 80% of the talking. It doesn't matter if I'm reading a
magazine or listening to my MP3 player--since he gets on after I
do, he'll always plunk himself down next to me and start
yakking.
I've partially gotten round this situation by waiting for the bus
to fill up a little before boarding at my stop, thereby increasing
the chances that I'll be able to secure an aisle seat, with the
window position already occupied, so there won't be an empty seat
next to mine when he boards later.
Doesn't always work, though, as there's no guarantee that the aisle
seat across from mine will be occupied by the time we get to his
stop...