I really like Syncthing, Nextcloud, Forgejo and Mailcow to collaborate with colleagues.
Kimai allows me to track hours and get paid.
Barrier allows me to use several computers at once.
Xen Orchestra is pretty much on par with VMWare stuff and way cheaper.
What other awesome software does allow you to work more efficiently in a business context and stays out of your way?
Not really client software but proxmox is damn useful. It's replaced any hypervisors at at least 2 companies I've been in IT at. It's not going to run your multi-national datacenters, but for the 2 or 4 locations on a low budget, with a need for Virtualization Proxmox makes it easy.