Online collaborative brainstorming with Popplet

Popplet is an online individual or collaborative visual brainstorming web 2.0 application with the ability to easily add text, photos, drawing and videos to a note (or popple). I stumbled upon this application while researching someone who has been helping me with my website via reddit and it looks pretty interesting. Downside being that it uses adobe flash (which is a dying format) and the mobile app is only available for the iPad. With that said though it looks like it could be a pretty useful tool in visualizing elearning development.

What do you think? Do you know of any other similar tools? Have you used Popplet? Let me know in the comments below!