I think this is a very interesting discussion. What is your preferred background color to work on. There's a few popular choices. First off there are people who like to work on pure white. I don't like this, it usually screws with your gamma perception, creating unfavorable palettes.
Then there's pure black. It tends to screw more with perceived shapes and silhouettes and if you're creating saturated artwork, it can be a little hard on the eyes, seemingly lacking cohesion. Here's what Henk Nieborg has to say about it, concerning his work on Flink:
"I Think there were a few reasons I started drawing everything on a black background, not just on the MegaDrive. First, back in those days I drew most of my gfx on a black background, I just liked that. You could get away with a lot of stuff by fading it into darkness. It's also quite handy when you're dealing with systems like the MegaDrive which didn't give you much memory to play with. I also prefer to draw to blackness because the contrast on the megadrive system was insane, if i would have anti-aliased everything to white i would have probably gone blind."
[ref]The next important one is the mid grey background. It's one of the more useful ones, because you're basically drawing onto the shade that has the most use in any palette. Almost any palette you create can be augmented by greys to buffer between shades with different hues. Since midvalues take up the biggest part of an image usually, drawing onto a midvalue grey canvas gives many advantages. One problem is that the lack of any hue can wash out the other colors, because you always try to work towards the background color subconsciously.
The obvious fix for the mid grey is a slightly tinted midvalue color. I think this might be the weapon of choice for most artists. Desaturated, dim midvalue backgrounds work easier, have no apparent issues and are probably the easiest on the eyes. I like to take a color that doesn't appear in the image to get a little hue contrast going, which usually turns up richer palettes.
Then there's the last one, which is a bit controversial, the saturated background. Many hate it, some swear by it. The usual suspect is pure magenta RGB(255,0,255), because it's used by many graphics libraries as the default background color. Obvious disadvantages are that the canvas can become tiring on the eyes and that the palette will usually go towards pure saturation. It doesn't seem to have any apparent advantages, yet I see myself turning back to it time and time again. Let me explain why.
As a lover of high saturation, high contrast palettes, I love how the magenta automatically pushes me to use bolder colors. I get very colorful palettes, with usually a good range, because you need them to get a good visibility of your image on the background.
My favored approach so far seems to be magenta for sprites, desaturated midvalue for other work. The extra oomph in the palette when working with magenta tends to work fine for sprites, since I like them to pop on top of the tiles or backgrounds you created.
Please share your own workflow in terms of background color.