Hannah quite frequently uses Duolingo as she has to constantly practice her Spanish. Duolingo is an interactive site that allows the user to learn any language and you can learn at your own pace.
Google is often used as well. Google allows you to connect to any browser, search for images, find definitions, etc. It is helpful when writing papers to find articles among millions of other benefits.
Lastly, Easy bib is a bibliography generator that allows you to scan your papers for grammatical errors and plagiarism. Hannah uses this for peer reviews, tutoring, personal assignments, etc.
Spanish dictionary is another source commonly used, but not as frequently as Duolingo.
Khan Academy is useful to find videos on specific topics within courses. For example, if you needed to find a video on covalent bonds in chemistry this would be a helpful resource.