I love the trane ductulator, you can google it and buy it for 15 bucks... gives you cfm/fpm , rectangular duct, round pipe.. I always just subtract my 15% for flex... but it hs served me well..
That is a good one, I'll still take the ACCA one though. Ever tried the RSES psychrometric calculator? Mine came with the SAM books. That's a cool tool to have.