Techsmith - www.techsmith.com/snagit - Screen capture; add effects and share.
Explain and send - https://chrome.google.com/explain and send - Capture webpages, write text, include arrows and circles and share it.
Szoter - szoter.com - Online image annotation tool.
Snaggy - snag.gy/ - Press to capture screen then paste to snaggy, save result and share with others.
Monosnap - monosnap.com - Cloud service to allow easy, convenient and rapid saving of screenshots.