A Network-on-chip topology designer written in HTML and JavaScript.
This gave me the opportunity to play with the <CANVAS> HTML element. I was quite impressed with the result.
It computes deadlock-free routing and produces configuration files for my own simulator.
The algorithm behind the deadlock free routing computation is also quite complex:
Andres Mejia, Jose Flich, José Duato, Sven-Arne Reinemo, Tor Skeie: Segment-based routing: an efficient fault-tolerant routing algorithm for meshes and tori. IPDPS 2006
Despite that, the JavaScript engine behind Chrome and Opera handles it fine as long as you don't exagerate with the size of the network.
It also works stand alone and can be downloaded from the attachments.