I'm happy with ZIM Desktop Wiki (http://zim-wiki.org/ http://zim-wiki.org/) and you can sync it's text files via Dropbox - bit of a raw solution I guess because

I'm happy with ZIM Desktop Wiki (http://zim-wiki.org/ http://zim-wiki.org/) and you can sync it's text files via Dropbox - bit of a raw solution I guess because there's no Android client - but text files are easy to parse in lots of interesting ways (e.g. I grep tasks marked as @phone and Dropbox them to my cellphone)