Hue and saturation adjustment layers...

Set the layer to colorize...

Note: If you want it to apply to a selection, make a selection and then make the layer... (The layer mask for the adjustment layer will be the selection.)

Adjust the brightness to make the colors darker or lighter.
Adjust the hue for which color you want.
And Adjust the saturation to move from grey to a vivid color.

Colorize simply tell the computer to make the color monochromatic using the hue value, instead of using the pixel data.

0 and 360 is red... 180 is therefore cyan
Also depending on your adobe profile settings, which color mode you are on and your monitor profile the colors seen and the colors real counter part may differ... so make sure you got them all set to a standard monitor profile, if you intend to print it out set the mode to CMYK BEFORE YOU PICK YOUR COLOUR!!! otherwise when you pick the color you may be shocked when the colors are a little off at the paint store but thats really for nit picking...)

oh god..is this a new tactic