Evernote is a great tool which I use all the time. As the name suggests it is good for storing notes but it is how it does it that I find useful. Most of the time I use it on my iPhone but it works the same way on other mobile devices like Android. I can use it on my computer by logging into the the evernote.com website or by using the app on my iPhone or iPad.
I like that I can take a photo of something and it appears in the note, if it is something like a business card or an article I have photographed it will use optical character recognition (OCR) so that I can search on the information if there is text in the photo. You can also add tags or type in some useful information into the note and search on this too. And it is quick, well so far, I guess it could slow down when I get loads of notes in there.
I can also share notes and categorize notes in the way you would put files into folders.
To see it in action watch my video below. For more video tutorials see my website www.jargonfreehelp.com