VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
Pennywise - Cross-platform application to open any website or media in a floating window
foobar2000 - An advanced freeware audio player for the Windows platform.
PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica
Winamp - Winamp is a media player that allows users to play multiple-file formats, arrange media in a varied file-management system, and play unique media with AAC encoding.
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.