All the NPHC have hand signs:
Omega Psi Phi
Kappa Alpha Psi
Delta Sigma Theta
Alpha Kappa Alpha
Alpha Phi Alpha (men) Sigma Gamm Rho (women)
Zeta Phi Beta
Zeta again, w/their brother, Phi Beta Sigma. They both sometime do the "dove" sign
Fianally, Iota Phi Theta and their...um..."fans" I guess, i dont know what to call them, they arent greek though
DISCLAIMER: I dont know any of these people...