Scripts n Styles received a major update today. The two big features added are LESS.js support and Dynamic Shortcodes! The “Global” Settings page now has a LESS editor with syntax highlighting (via CodeMirror) and on-the-fly compiling so you can see how it’ll be outputted on the theme-side. The per-page meta-box has gained a new tab in which you can create one-off shortcodes which can contain arbitrary HTML content.
Scripts n Styles is a free OpenSource GPL project that you can fork and contribute to on github! (You can also fork and contribute to CodeMirror and LESS.js)
As a Shortcode example: I placed the following html into the Shortcodes tab and gave it the name “tweet test”.
I then use the shortcode ] to display: