At work: JIRA and Confluence. I write a personal weekly "top 3" on a public confluence page; my team has JIRA boards for task tracking. For things like meeting notes I use textile files (textile because it's easy to transfer to Confluence if I need to) with a work-supplied cloud backup.
Info on how to run up a project, troubleshooting, releasing etc all goes into the readme in the git repo.
Personal stuff: Google Keep; and reference files/code library live in a git repo (would prefer dropbox but that is blocked at work due to some network security policies).