remote mail client based on Open Standards or web email like Gmail, Yahoo! etc.
###Instant Messaging. Text, voice, video Yahoo! Messenger, IRC, Jabber/XMPP, Microsoft, Apple Facetime, Google Hangouts and Android Duo (1:1), WhatsApp, Facebook IM, Skype, Hangouts, Slack Video
###Video conferencing Jitsi "painless set up, apps for iOS and Android though the web version’s pretty good, from what I’ve seen.", or "not bad. Other alternatives are talky.io and whereby.com which both work on the web without needing an app and are generally reliable"
https://palava.tv, is open source and uses webrtc in a web browser. It is simplistic video communication with your friends and colleagues from within your browser. No registration or browser plugin required.
Bigger groups, commercial services: Webex, Zoom.
If you have high information security requirements, take great care what you choose.
Sound and video works best with headphones, so you don’t get feedback from speakers to microphone which can cause echoes or high-pitched screaming. If you aren't speaking, mute your mic. to reduce background noise for everyone else or use noise-cancelling headphones
Web documents - Microsoft Office 365, Google Docs
Free software: Libre Office, save as a file type compatible with your normal office suite
Planning software: Trello, Jira
On-line storage - Dropbox, Google Drive
Shared Wikis (a network of linked pages) and databases.
Windows has built in Remote Desktop though the issues you’d likely have would be to do with the firewall (port 3389). There is a 1 user limit on some Windows licences, so it’s essential that you always log out or nobody else can log in.
Xfreerdp is a Linux client for Windows RDP servers. Other Linux RDP clients are available. There may be RDP servers, so Windows PCs that aren’t allowed to have software installed can be used to access Linux.
"For Linux desktops, we offer VNC or X2Go."
X2Go operates through SSH so it is secure by default.
X11vnc is a good VNC client for single user Linux machines, since you get access to the graphics card.