As WYSIWYG wrote, energy is the answer, but to clarify the dependence of energy from momentum... sorry, the dependence of frequency from wavelength, have a look at the animation on this web page: http://www.acs.psu.edu/drussell/Demos/wave-x-t/wave-x-t.html, posted here in what I believe complies with fair use legislation:
It represents a sinusoidal wave, the basic component of any disturbance (as long as you can count on linearity, but that's another matter...).
Frequency tells you how fast the red dot goes up and down. This is what a receptor put in that specific position will sense: a disturbance (here it's the height of a string, in your case the amplitude of the electric field) changing $\nu$ times per second.
Wavelength, on the other hand, tells you how far the maxima and minima of the sinusoid are separated in the medium. In this case, two subsequent crests are separated by $\lambda$ meters. For a given disturbance frequency, this number depends on how fast the wave is allowed to travel in the medium. A slow wave will have a shorter wavelength (because it will travel a smaller distance in space during the time the red dot completes a cycle); conversely, a fast wave will have a longer wavelength.
Note: the speed can depend on the frequency of the disturbance - in that case the medium is said to be 'dispersive' and the relation between frequency and wavelength (or energy and momentum, or - if you are into quantum physics - between energy E and wavenumber k) is called a 'dispersion relation'.
In an isotropic homogeneous medium, the speed is the same in every point and in any direction and you can write
$$\lambda(\nu) = c(\nu) / \nu $$
The frequency is determined by the physical process in the source. It's very hard to change the frequency (i.e. the color, in the visible) of a light wave - you have to resort to nonlinear effects to do that. The wavelength is the result of the interaction with the medium, and changes all the time. But it's customary to express a sort of implied equivalence between frequency and wavelength based on the behavior the light wave would have in vacuum. Hence, when one says 550 nm photon, he is usually implying a photon with en energy corresponding to
$$E = h \ \nu = h \ c_0 /\lambda = 4.226 10^-19 \ J = 2.64 \ eV$$
Where $c_0$ is the speed of light in vacuo.
(Note: the latter value is computed from the one before diving by the charge of the electron).