Not me this year
The year before last I saw both Venus Williams AND Leyton Hewitt on centre court - with Mark of course - I have been once before that with my Mum too.
The year I went with Mark we got Mark Philippousis' autograph on a giant tennis ball

The ticketing for Wimbledon is done through a ballot - you send an application in and they randomly select people and offer them seats for a certain day (obviously they can't tell you who will be playing) - you can then refuse them, (but now I think ppl sell them on ebay instead) any returned tickets are put in a second ballot.
We were not offered any tickets this year or last - it's the luck of the draw