Bopping around the internets today, I ran across this excellent piece on 7AMKickoff about Martin Keown. If you're a more recently minted fan of Arsenal, you might not remember that much about him; his second tenure at Arsenal roughly coincided with my Arsenal fandom beginning, so I have a pretty good recollection of his later years, at least.
This piece does a great job of filling in the whole story, though - his start with Arsenal, his move to Villa in 1986 - he was sold on the cheap when George Graham took offense to Keown's asking for a £50 a week raise! - and his time both there and at Everton before returning to Arsenal in 1993.
He moved back in time for Arsenal's Cup Double win that year, but was cup-tied in both cups, so he didn't get any medals. That would be one of the last times he would not win things with Arsenal, though, as he spent the rest of his career solidifying and anchoring an Arsenal defense the likes of which hasn't been seen since...until this season.
Anyway, it's an excellent read, it features video of the van Nistelrooy incident, and if you've been curious about a bit of Arsenal history, you should go learn a thing or three.