Fonts, Drivers, Dictionaries
AATSEEL's Russification page has useful information about configuring your computer to work with Cyrillic. Includes information for Windows and Macintosh systems.
ConvertCyrillic.com is a tool for converting among systems for representing Cyrillic, including KOI8, CP1251, Unicode, and transliteration. Also includes a keyboard where Cyrillic characters can be manually entered, as well as a translation aid that links all words in a Russian text to a dictionary.
Translation and Dictionaries
Lingvo by ABBYY is a powerful online dictionary with several specialized lexicons.
Yandex.ru's dictionary page offers online versions of dictionaries, encyclopedias, and specialized references.
Словарь русского языка в 4-х т. (Под ред. А. П. Евгеньевой.— М.: Рус. яз.; Полиграфресурсы, 1999)
Поэтический словарь А. П. Квятковского. (Науч. ред. И. Роднянская. — М.: Сов. Энцикл., 1966) - a reference of poetic terminology.
Other Language Resources
ETS.ru maintains a frequently-updated collection of Russian neologisms.
Rusyaz.ru has resources related to the rules of Russian orthography and punctuation.