The Russian alphabet has 33 letters in which two are not letters at all but rather a "hard" and "soft" sign that influences the pronunciation of the preceding or following letter. Online resources can help you become familiar with the letters and their pronunciation. Practice Russian.com offers a variety of free resources to learn the alphabet and practice basic Russian. Click on lesson one to begin the alphabet exercises, or if your level is a little higher you can go straight to the crosswords and search a words. This site is free, and does not require registration.
The Hello World language websites offers a wide variety of free online games and resources. The only drawback is that it is aimed at children rather than adult learners. The site can still be useful however, even if you are an adult learner and not searching for a site for your child. Children's language games are meant to capture the attention of children, but adults can use them as well.
RussianFlashcards.com offers a two-tier system of free and paid subscriptions. The free option comes with audio for a limited amount of time, paid is unlimited. The best part about this site is that it is aimed at all levels, and allows you to practice words followed by sentences in games and constant review.
For the beginner or the advanced learner, podcasts are an excellent resource to learn the language. Many are free, and some require registration, however russianpod101's youtube channel has a great collection of free videos to watch for vocabulary building.