Russian Cell Phones
It's simply ridiculous to try to get around Russia without local Russian cell phones... You arrive and your airport pickup isn't there... Your date needs to text you to say she's running late (or vice versa)... and on and on... Seriously, it's just crazy to not have a cell phone there!
You have two or three options for solving this problem. The first is simply use your normal cell phone and service and pay their INSANE international roaming charges. If money is no object for you, and you already have a quad-band cell phone that has full international capabilities (AT&T and T-Mobile have both worked for me, and most smartphones now are quad-band), then this may be your easiest option.
If cost matters at all, then you have two options, and both are dirt cheap.
The simplest of your options regarding Russian cell phones is to simply buy a cheap phone at the airport or other nearest cell phone vendor. They're everywhere. You can probably find a simple phone for under $60 USD and a SIM chip (almost always sold separately there) for $2-$3 USD.
By the way, whether you use a phone that you buy there or just use a Russian SIM chip in your U.S. phone (more on that in a moment), all usage is pre-paid. When you buy the SIM chip you also need to buy some credits. Usually these come in the form of scratch-off cards where you scratch off the coating over the secret recharge code that you enter in the phone. Just ask the SIM chip vendor to show you how to do this, and how to check the remaining minutes at any given time.
The final option you have for meeting your cell phone communication needs while in Russia is to just use your own U.S. phone. If you have an UNLOCKED, QUAD-BAND, U.S. cell phone that operates with a SIM chip (i.e. AT&T and T-Mobile), you are in luck.
In this case you can usually buy the local SIM chip for $2-$3 USD from a vendor right there in the airport, pop it into your phone, and you have a local, pre-paid cell phone (most new SIM chips come with some credit already on them, but you should probably buy an additional $10 USD of credit from the same vendor). Cell phone vendors at airports typically speak at least a little English and can help you set up your SIM card and credits.
If you have a quad-band cell phone from AT&T or T-Mobile, it already works on a SIM chip (Verizon and Sprint do not use SIM chips), but is probably NOT "unlocked". And this can be a problem because to temporarily convert U.S. cell phones into Russian cell phones, they MUST be unlocked.
Almost all U.S. cell phones start off LOCKED.
There is a little something about the inner workings of U.S. cell phone companies that will be helpful for you to know when it comes to getting your phone unlocked.... Except in special cases, almost any time you buy a phone from a U.S. cell carrier, they subsidize much of the phone's cost.
A Samsung Galaxy and iPhone typically retail in the $600-$800 range. If you get one of those for $200 (or less) at AT&T, it's because they get the remaining $500 or so out of you in the form of your monthly bill over the contract term (usually 2 years). One way they can enforce that contract is to keep the phone locked to their network. You can't get the phone for $200 then immediately cancel the contract.
So how then do you get it unlocked? If you have had the phone for more than a year or two, your cell company will probably unlock it for you free, or if you bought the phone at the unsubsidized price (i.e. you paid the whole $600-$800). You just call them and ask if your phone qualifies for unlocking, and if it does, they'll walk you through it right over the phone. I've unlocked many phones that way now and it has worked like a charm.
If your phone doesn't qualify for unlocking it is still possible to unlock it. You can investigate these options yourself by just doing an internet search for "Unlock cell phone" and you will get more options than you could ever need.