Here are two other brief overviews of OCaml, aimed at readers who already have some programming experience. Here are two more, even briefer.
Here's a more detailed tutorial for OCaml.
The start of the OCaml Reference Manual has another tutorial.
Jason Hickey has posted a draft of a nice book introducing OCaml.
FAQs for OCaml Beginners, and a few more. Also FAQs for OCaml Experts.
Some more: OCaml Basics; Chapter 1 of OCaml for Scientists.