I wish I had had access to this in high school and college. I did have a website that would format citations, but it wasn't always correct and searching a book is much faster. I probably wouldn't use this with my students, but I'll keep it in mind when I go for my master's degree.
I chose to explore two Spanish-English dictionary apps: WordReference and Dictionary by Bravolol. Both apps had very similar features. They give you several translation options, will demonstrate how to pronounce the new word, and both give examples of use. Despite similarities, I would choose WordReference. It has a forum where you can find translations that wouldn't be found in the dictionary (phrases, slang). WordReference will include where that translation is used, if it is formal or slang, and if it can be considered offensive. With so many Spanish speaking countries, these are useful tools. It allows you to search for abbreviations. Also, it provides more examples than the dictionary app.
Diigo has been very useful. I had a bad habit of putting all sites on my bookmarks bar and usually lost or fogot what was there. The tags make looking for bookmarks very easy. I usually tag the sites several different ways to be sure I can find it when I need it. Also,e description helps me remember what was on the site quickly without tKing the time to explore the site again. Also, I use Pinterest to keep track of resources. I have more links and am more comfortable with Pinterest, but I am building a large library on Diigo. The positive of Diigo is you aren't limited to a site giving you permission to save like on Pinterest. Also, you aren't limited to what other people have pinned and found important.