Our Upcoming Events sidebar has a link to Pesach questions, with the tags passover and passover-seder-hagada. Should it be expanded to include other Pesach-related tags?
I've stumbled upon:
four-sons
marror-bitter-herbs
matzah
gebrochts
kitniyos-semigrain-legume
chametz-leaven
four-cups-wine
though there may very well be others I've missed.