Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Tabbles - Tabbles use tags to organize and find files along with your colleagues.
allTags - allTags is a free, tag based file management application.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
Elyse - The free version allows up to 30 tags.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.