Before entering or leaving Russia you have to complete a Customs Declaration. The theory is that that you do this to declare what you are taking in so that you can later get it out again as well as declaring the things that you shouldn't be taking in at all.
There is a Green Channel and a Red Channel at SVO-2 in Moscow. I'm not sure what the purpose of the Green Channel is because when we took it we were let through without our declarations being inspected. No-one seemed to take the green channel so we did to speed things up. On refection this was probably the wrong thing to do because you won't have a validated declaration for when you leave.
When we did leave we gave both declarations to the customs officer and just told me to write NO where I had just ruled out the answer spaces for the questions pertaining to weapons, drugs, art and Roubles. Your baggage is xrayed but stuff in your clothing is not checked. I was a bit concerned that I might have some explaining to do should they find my CD player, mobile phone or GPS (all in my jacket).
Trying to leave with Roubles will ensure that you'll have to join the queue again after changing them or wasting them. As we were pushed for time I chose to waste them. The one queue at the bank already had 5 people in it. I gave a bit more than 1000 Roubles (about 25c, a small pile of various notes) to a puzzled kiosk girl, who said 'kak?' (what?).
As we stood in one queue a film crew who had pages of stuff declared told us that we should choose another queue because they were 'going to take an hour -- at least'. Another one said 'it's the price we have to pay'.
Another puzzle is that the reverse side of the from has an area to declare various items that you're carrying in with you. However this is headed by FOR OFFICIAL USE. I filled it in anyway, given I assumed it would have to be done anyway.
I think you are supposed to also hand in the green currency change forms to show what money you have changed. There is a space for this on the reverse side of the decalartion. I handed them in and I guess they were given back to me because I've found all of them in my jacket.
Even though my paperwork was a mess the Customs Official let me pass without problem.