I think it would be useful for some languages like Italian to have conjugation charts. Like a chart that labels the endings when the verb is not it it's infinitive -are, -ere, or -ire form. I find that I have a hard time keeping track of the endings for the verbs and it is easier for me to see it in a chart. It would be nice to have one whenever it presents a new tense like past or something, it could have the new chart for an example verb.
I have not stuck to one site per language but just googled what I needed. http://en.lmgtfy.com/?q=italian+conjugation+present+tense is an obvious answer for the OP's question.
http://www.wordreference.com/ is great for explanations of phrases and examples of usage.
http://www.duden.de/ is good for looking up German words, however, this is a German-German resource.
http://en.wikipedia.org/... wiki really rocks sometimes.