Hmmm... let me think...
Fryderyk (like Chopin:), Fryderyka too (although not so popular as Fryderyk), Felicja (as was said before) and Felicjan (male version... could be called: Felek), Franciszek and Franciszka (male and female version of Francis or Frank). Other are: Fabian, Feliks , Filip , Florian...
I guess Filip and Franciszek would be the 2 most popular nowadays (among the names starting with F of course:)
