Tim Gowers says it’s
a website in memory of Maryam Mirzahkani. I don’t mean that it is a memorial website: rather, it has taken an important aspect of her life — her interaction with other like-minded mathematicians at a young age — and aims to facilitate such interactions for others, by the setting up of maths4maryams groups.
In short, you sign up to the website, either start or join a group, and solve maths problems together. In particular, they’re proposing Mirzakhani’s birthday, the 12th of May, as “Mathematics Friendship Day”, when friends solve maths problems together.
More information at maths4maryams.org
via Tim Gowers on Google+