For German,
this site covers quite a bit and is worth a look (it has Spanish lessons, too, but I've only poked around the German section). I'd recommend checking out the Youtube channels "Get Germanized" and "DontTrustTheRabbit", too -- they are German native speakers talking (in English) about the German language and culture. "Wanted Adventure" is another channel to check out if you're interested in the culture, although there isn't much about the language itself.
There's also a
German thread here on CS where I'm sure you could find someone to help out if you're having trouble with something! You're welcome to PM me as well if you'd like some advice or lessons or practice or whatnot. c: I'm pretty comfortable with the language and should definitely be able to help with most of the grammar, but just know that I'm not a native speaker and am still learning stuff myself.
For Russian, I'm still a beginner and not a particularly competent one yet, but I've been using
this site for learning online and found it pretty helpful. Mostly I've actually been working from a book, though:
The New Penguin Russian Course. It's unfortunately getting a little old (1996), so some of the words and cultural info might be outdated at this point, but it's still a very well-designed course and I would absolutely recommend it if you don't mind the good ol' pen-and-paper method. ^^
For the others, I'm afraid I can't really help. But two websites you might find useful are
Reverso and
Duolingo. I use Reverso all the time: it's basically an online dictionary, so it wouldn't be your main learning source, but it has several languages and I love how it also gives you phrases and tons of context samples to see how words are actually used, as well as conjugation tables for most verbs! Duolingo I'm personally not all that impressed by, to be honest, but it's free and I've seen a lot of language learners swear by it, so it's at least worth a try. x3 If you do like it, then I would just recommend using it as a supplement to a more in-depth course if possible rather than just on it's own.
And here on CS, there's the
Language Tutor thread for looking for someone to help you learn different languages. ^^ Good luck!