Most illogical: If you look closely at the devastated Magic Box, there's a smouldering William Shatner book on the floor. Does this mean Giles was a closet Trekkie? He does appear to have beamed in from Devonshire...
All you need is love: Just for once, Buffy doesn't save the world. Instead, Xander uses a cunning mixture of infant school memories and saying "I love you" a lot to turn Willow (and her hair) from the dark side. Meanwhile, Buffy is stuck in a hole with Dawn.
References: Jeeves was the butler in P.G Wodehouse's Jeeves and Wooster series of novels. Black-eyed girl, Xander's name for Willow is probably a play on the Van Morrison song Brown-Eyed Girl and Willow's dismissal of Andrew and Jonathan, "dead men walking," refers the to the film Dead Man Walking, starring Susan Sarrandon and Sean Penn.
End games: Grave is the first Buffy season finale not written by Joss Whedon. He'd been very busy with Firefly, and probably needed a bit of a lie down by this point. He only wrote one episode - Once More, With Feeling - for season six. It was the best one, though.
Cryptic in-joke: Xander attempts to break into the Alpert mausoleum. A prop used throughout the series, the Alpert mausoleum is named after Buffy producer Marc David Alpert - even though he's still very much alive.
Soul man: After a deeply spiritual set of trials - which mainly involved kicking and punching scary creatures, plus letting big beetles crawl all over him - Spike gets his soul back. Does this mean he'll feel the need to set up a detective agency on Los Angeles? Or perhaps start writing 'bloody awful' poetry again.
Music to die for: The song played at the end of the episode is Prayer Of St. Francis, by Sarah McLachlan. It's a rare track which appears on the bonus disc originally included with the limited edition double CD release of her Surfacing album in 1997.
Sarah's music was used previously on Buffy - the track Full of Grace, also from Surfacing, appeared at the end of Becoming part two.