Recently I've noticed a sound coming from (I think) the right front wheel area. Most audible when decelerating down to a stop. Sounds like when we were young and put a playing card in the spokes of our bike. Can't hear it really when I'm up to speed. I looked and couldn't see anything rubbing. Any ideas??

 

Jack it up, rest front axle on jack stands and rotate wheel, check side to side play (wiggling back and forth), and inspect brake pads and rotors for excessive wear. Check your front drive shaft for unusual movement, sloppiness at cardan joint or any joint for that matter, but normally, a flapping sound is the cardan joint lobes making contact.