This is really great: an OO extension for DrScheme built on Tiny-CLOS (where object-oriented here means the typical object+functional mix from CLOS — not those minimal OO systems from typical class-based languages). Very nice. And a large pile of additional tools and utilities on top. Basically you could say the programmer tried to implement large parts of Common Lisp in DrScheme. Nice, since I'm an old CL fan and Scheme fan, here I get the best of both worlds.
Unfortunately the system hasn't been extended to the GUI system, which still exists in the more classical OO form from DrScheme. A CLOS wrapper around it (or perhaps something like a tiny CLIM? Yeah, yeah, I'll be quiet, but one is allowed to dream) wouldn't be bad either.
Somehow DrScheme reminds me fatally of my nice Xerox 1186-compatible Lisp machines with their mix of Interlisp-D and Common Lisp in the operating system. There too the basic stuff is implemented in Interlisp-D (in DrScheme it's Scheme) and then Common Lisp is layered on top (in DrScheme then Swindle). Very nice approach.
And one more funny thing: a small graphical tool that visualizes lambda calculus. Programming with colored blocks to make things clear.
I think I like DrScheme