Three recently-created Wikipedia articles

Gilbert tessellation, a mathematical model of mud crack formation closely related to motorcycle graphs.

Citation graph, a graph of academic papers and their citations to each other.

Double Bubble conjecture (now a theorem), the fact that the minimum-surface-area enclosure for any two volumes takes the form of three spherical patches meeting in a circle.

They're all a bit short, in need of more detail and better illustrations, but still I think more useful than not having an article at all.