Pennywise - Cross-platform application to open any website or media in a floating window
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.
PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.
Shopify - Shopify is a powerful ecommerce platform that includes everything you need to create an online store and sell online. Try it free for 14 days.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.