If you are looking for examples, Ocsigen Start is probably the best starting point. It contains an app skeleton for getting you started and plenty of examples for learning Ocsigen .
The Eliom open-source applications that come to mind are the link-sharing site Cumulus and the wiki engine Ocsimore.
There are quite a few open source applications using
js_of_ocaml, e.g., Try OCaml, JsCoq, CueKeeper, and a TODO MVC implementation.
Additionally, a look at OPAM will reveal many libraries and frameworks that use some part of Ocsigen. And of course there are quite a few non-open-source projects. For example, BeSport is an entire social network built with Ocsigen and OCaml technologies.