Here's a video of VisiJax in action:
It's an incredibly simple app - all you can do with it is create tables and edit them. Columns are called "page types" and rows are called "variables." This is because I created this as the front end to a code generator concerned with page types and variables. Only after actually building it did I realize that I'd created a general-purpose table editor which might be useful for general spreadsheet applications. It's not a staggering work of genius by any means, but if you needed to build arbitrary spreadsheet-like apps, it's essentially scaffolding for those types of projects.
So, I named it after VisiCalc, the Apple II app which was the first spreadsheet, and put it up on GitHub. The name is kind of a misnomer, though, as VisiJax just stores data, without executing formulas. (Adding formulas to VisiJax would be pretty trivial, though, and an interesting way to cut your teeth if you're new to Rails.)