I futz around with OCaml. Once in a while. Futz. There's a lot of interesting libraries and open source projects happening around it. Here's a consolidation of links I've found interesting:

OCaml Homepage
Setting up OCaml for Apple OSX
LablGTK - gtk interface.
• A very nice GTK+ 2.0 tutorial.
• Flying Frog's Consultancy's Introduction to OCaml.
Ocamlnet - collection of libraries for networking.
software - Personal site with some open sourced projects.
• Labltk mini tutorial.
OCaml Chipmunk - OCaml bindings to the C libs.
Ocsigen OCaml based web server. Also has an accompanying paper that's pretty interesting.
http://et.redhat.com/~rjones/ - Virtual machine management
http://tech.motion-twin.com/xmllight.html
Zippers
PG'Ocaml tutorial for postgresql.
OcamlSDL
• Wrapping C functions tutorial
Design Patterns in Ocaml