Note that Monthly and Weekly challenges run in March, too.
This is an annual drawing challenge running from March 1st to 31st.
What's the challenge? Draw a robots, ideally daily.
Where, how to take part: Post anywhere using the tag “marchofrobots”
Official website: marchofrobots.com
This is an annual writing-related challenge running from March 1st to 31st
What's the challenge? Spend a total of 50 hours editing a novel (such as last November’s NaNoWriMo manuscript)
Where/How to take part: Sign up on official page www.nanoedmo.com and track time spent editing there