Suggestions: Including genders for nouns in hints
When mousing over "sky" for example, the popup could read "(der) Himmel" or "Himmel (masc.)" rather than just "Himmel".
When translating from English to German, it can be rather annoying having to go to google translate and and type in "the [noun]" to figure out the noun's gender. Sometimes a noun is rarely used with articles so it can take a while before you realize you were assuming the wrong gender all along, at which point it's been sort of imprinted in your brain.
I love Wiktionary, which is available in many languages. Nouns are declined, verbs conjugated. Sample sentences, etymology. Definitions also, but do note that the pages are entirely in the target language, so no direct translations. I've found Wiktionary especially valuable in Russian. See https://de.wiktionary.org/wiki/Himmel