Titanium is a feature-rich, reliable framework for creating GUIs within ComputerCraft. Titanium offers a quick and easy experience for those that just want to jump in, however more powerful tools are on standby if you need them.
Titanium is currently in beta and your feedback, bug reports, suggestions (via issues) and merge requests are welcomed.
The Titanium website is loaded with useful guides, and class reference documentation (automatically kept up to date with latest Titanium installation). Head on over there now to get started with Titanium.