Where do I find a link to download a modern russian dictionary like the one that google provides for english?

Do you mean a glossary (Ru-Ru) or a translation dictionary (En-Ru)? For the former, check out the resources at http://gramota.ru. (I'm afraid there might be no downloads, but it's a start.) For the latter, I'm not sure there are legally redistributable dictionaries except mueller7-dict, which is an English → Russian dictionary.