I got waitlisted at fordham. should i write them a letter?

Absolutely write them a letter, and send it, hardcopy, via postal mail - this is too important to send electronically. If they're your first choice school, make sure you tell them that. If anything has improved re: your application since you applied (won an award, French grade went up, etc.) tell them so. If you can get one more teacher recommendation letter this quickly, include it.