You need a visa if your not from the CIS or Israel. Others will need a visa and an invitation.
You will need to pay for the invitation, then pay the consulate and you will need to register when you arrive. Regulations are very painful, do not expect to travel very far without some sort of support. The visa regulations for Russia are costly, tedious and take a lot of time.
If you wish to travel for longer than 30 days you may need establish some "contacts" who can help you arrange a business or special visa.
Embassy of the Russian Federation, main page
Russian embassies
List of charges and details
