Nuclear activity in galaxies is believed to be closely linked to the availability of (molecular) gas at the very center. Bars, which are commonly observed in spiral galaxies, are thought to play a key role in this process by transporting gas from the outer large-scale disk to the central kiloparsec. Less well-established is the fueling of the inner regions; secondary or inner bars were first proposed to bridge the last few 100 pc, but recently other mechanisms, such as m=1 modes, and/or gas density waves have been suggested to be equally or more important. Recent observations of the molecular gas kinematics in the central regions of nearby galaxies using mm-interferometers allow us to directly test the theories against observations.