There are a few options:
- Tuareg for emacs was already mentioned: http://tuareg.forge.ocamlcore.org/
- vim has a few options for OCaml integration, with one good example available here: http://www.ocaml.info/software.html#vim
- OcaIDE seems to be the best option for Eclipse: http://www.algo-prog.info/ocaide/
- Geany, Komodo Edit and a number of other editors have syntax highlighting support for OCaml and some extra IDE-like features which are independent of the programming language being used. Most of these have limited OCaml-specific support.
OCaml is not dead. Some of the more vocal industry users of OCaml are XenSource/Citrix and Jane St. Capital. The language does not receive the same public and community evangelism that some other languages receive.
