interactive
I have a healthy interest in mathematics on the internet:
Various
I also have smaller projects:
An atlas for $\mathop{\mathrm{Spec}}\mathbb{Z}[x]$, a collection of pictures for the geometric intuition behind $\mathop{\mathrm{Spec}}\mathbb{Z}[x]$
comparison of topologies on $\mathrm{Sch}/S$, an incomplete comparison of all the Grothendieck topologies on the category of schemes I could find, together with their properties
cohomology of twists of the structure sheaf and Hodge diamonds for complete intersections: in the case of a complete intersection it is not too difficult to compute the dimensions of the cohomology spaces of (twists of) the structure sheaf, thereby visualising Serre duality, and similarly one can compute the Hodge diamond
comparison tables for the Stacks project (work in progress): the goal is to have tables comparing properties and providing a structured means of accessing the Stacks project, the first example being properties of morphisms and their preservation properties (under composition, base change, fpqc descent, ...)