Brown, Nicholas Russian Learners' Dictionary (0415137926)
This dictionary contains 10,000 Russian words in order of importance starting with the most common and finishing with words that occur about 8 times in a million. All the words have English translations, many have examples of usage and the entries include information on stress and grammatical irregularities. There is also a complete alphabetical index to the words in the list.
A learner who knows all or most of these 10,000 words can be regarded as competent in Russian for all normal purposes. The list takes you from a beginner's core vocabulary through to postgraduate level.