bradyhall007 - 7:21 pm on Dec 22, 2009 (gmt 0)

The above user is close to being correct. Neutrals and colors that will allow the emphasis of the site to be directed to the artwork and not your 'fancy' buttons, text boxes and obnoxious background patterns. [colorschemer.com...]
Color schemer is a nice program for generating color pallettes (triads, complimentary, pastels), but I hesitate to even recommend it to you because you are right to look to the example of museums. Warm greys, whites, black, solid colors or even cinder block (like my old art school used to prefer).
Again, this is subjective to what art you are hanging on the wall. If the painting is all blues and greys, but is making a statement about the color orange, you want to be sensitive to that and provide a background that will let the work 'speak'. (ie dont make a rusty orange background that will blow away the very thing the picture was all about - sublety and the relative hues of appartent orange in the absence of anything chromatic nearby.)
If you need real world examples:
[ecx.images-amazon.com...]
The 'Wow' seriers books all have subtle backgrounds because the are emphasizing the foreground and textural effects that photoshop can accomplish.