fwiw, anecdotally speaking, i've seen a lot more "boyfriend sweater curse proven!
" posts than "boyfriend sweater curse a MYTH" posts.
i think the way to break it is to make sure you give the sweater to him as a wedding present.
as for other superstitions... oh, i don't know. there's one in theatre about knitting being unlucky onstage, possibly because small acessories are easy for stagehands to trip over in the dark? then there's the one about never, ever setting your knitting down when you're in the middle of a row, for fear that you will pick it up and start knitting the wrong way--back over the partial row you just did, if you see what i mean.
i think it would be fun to make up some superstitions, some silly ones, to frighten the newbies with. and then we'll make our daughters fiber addicts, and one day they'll come to us and say, mom, did you ever hear that you should never knit while eating peanuts!? and you will laugh and say yes, i am the reason for that, in fact. and she will look at you in wide-eyes, childlike wonder before calling the loony crew on you.