I did a search on here and found these.
Fatal Charms by Ashlee
http://spikeluver.com/SpuffyRealm/viewstory.php?sid=14021&warning=NC-17Summary: On a quest to win back his dark princess, Spike plans on resorting to magic, if that's what it takes. What he doesn't expect is for something to go terribly wrong, causing the spell to target the one girl he's meant to hate. How will Buffy react when the spell is lifted and she finds herself in a compromising position? A rewrite of Bewitched, Bothered and Bewildered Complete
Something Blue-ish by Lenore
http://spikeluver.com/SpuffyRealm/viewstory.php?sid=26046Summary: Challenge # 274 on the Bloodshedverse. "In Season 4's episode "Something Blue" Willow's spell works on Buffy but not on Spike write us a fic of Buffy chasing around a terrified Spike demanding he marry her. To the point that she claims him only seconds before the spell ends :P Must Haves 1. Poor Spike is sooooo not interested :P" Complete
Someone Blue by Dorians Kitten
http://spikeluver.com/SpuffyRealm/viewstory.php?sid=37057Summary: Set immediately following Willow's Will be Done spell during Something Blue (season four) and going AU from there. Free will has been returned, everyone's feeling's should be their own and yet Spike is left feeling the pain of a broken engagement. His wounded heart is no secret, but the Scoobies are at a loss to figure out why. Can they find a way to break the spell or will Buffy be stuck with a lovesick vampire sidekick? WIP