Our existing backsplash is beige travertine tiles (actually quite nice) that has cream outlets and outlet covers, and looks good. Done by the stager before we bought the house, who certainly didn't try matching anything, but I think it's fine as it is. The photograph idea seems really strange to me, but I guess it depends on how much you mind noticing your outlets.

I used a dark grey backsplash tile in my bathroom, and used a Krylon spray paint in grey on both the outlet & outlet cover. Let me just say the outlet (GFI) was a real pain to tape off, but it does look nice and matches great :)

What doesn't look great is how the outlet physically sits in the tile backsplash accent, but that's a whole different story...

Instead of plastic outlet covers you can consider resin ones that look like stone, metal ones that match the cabinet hardware, or porcelain if you can find ones that are close to the color of the ceramic tile if you go that route. I think these would look nicer and wear better than the picture under the plastic method.

This link shows some of the "stone" versions:
http://www.wallplatewarehouse.com/textured-finish.html?gclid=COf_58rOx58CFRHxDAodGzFl3g

I got the 'stone look' resin ones for the backsplash (Loews) and oil rubbed bronze outlet and switchplate covers (Target - good price!) for all over the house. They look much nicer IMHO than plastic.

Places like switchplates.com, switchplatesuperstore.com, etc. will give you lots of ideas. (Check out the Fine Art series on switchplates.com if you like art -- great colors under Van Gogh and Kandinsky.)

Are you doing the tiles yourself? I'm wondering if it's possible for a good tile pro to cut one of your tiles to the right size, cut out the inside to fit the outlet, and drill holes in the right spots for the screws. It's a long shot, but would look nice!

Here's a picture of the stone look outlet cover:

{{gwi:1583079}}

Until I did this kitchen remodel, I thought outlet covers just came in two standard colors, white and off-white (the off-white being that yellowy color that everyone's had for the past million years).

Then I discovered that they came in "almond", readily available at most hardware stores, HD, etc. It works well with my light travertine. The "almond" isn't noticeable. If my stone was like chicagoans, I would have gone with the stone look covers (which looks great on hers!), but mine's a little smoother, so it would have stood out more.

Bring your tile to HD and see how it looks against the different types and colors. Maybe you'll find one easily and not have to do too much work on this decision. One can hope!!

I actually bought real marble outlet covers online and they match my backsplash fine.

You can order travertine outlet covers. But you may have to pull the outlet forward a bit because they will be thick.

Try either Switchhits or Wallplate Warehouse.

Switchhits

But be warned...you might end up with all sorts of outlet covers! I just can't have plain ordinary white ones myself. It's too boring. ;)

Here is a link that might be useful: Wallplate Warehouse

thanks for all the good ideas :)