This isn’t going to be a super comprehensive list for now, but these are some of my favorite websites and resources online. There are a LOT more websites, including sites for all the volcano observatories around the world. I will be adding those in eventually, but for now, this is a short list of resources and sites I frequent.
Global Volcanism Program: The best place to research general volcano information for all the volcanoes across the world. Also has updates and information on newly active volcanoes.
GISP2 Volcanic So2 Data: This is a simple webpage that displays data in the Ice Core Records of Greenland of Sulfur dioxide over the last 110,000 years. This can be useful when for trying to track large eruption signatures. One small caveat is that the records become more sparse the further away from present, so there may be some notable so2 spikes that are not accounted for in here.
Wired Eruptions: A blog by volcanologist Erik Klemetti detailing all things volcanic in nature.
Volcano Cafe: A volcano blog that has a great commentor community associated with it.
Volcano Hotspot: A wonderful blog that is regularly updated.