Ocamlnet is an enhanced system platform library for Ocaml. As the name suggests, large parts of it have to do with network programming, but it is actually not restricted to this. Other parts deal with the management of multiple worker processes, and the interaction with other programs running on the same machine. You can also view Ocamlnet as an extension of the system interface as provided by the Unix module of the standard library.

So, which kind of applications can profit from Ocamlnet?

Web applications can use the netcgi2 library which provides all core functionality like connecting to web servers, decomposing web requests, and emitting web data. With the [nethttpd] library Ocamlnet even includes a little web server of its own, so stand-alone Ocaml programs can respond to HTTP requests. This is especially interesting for providing high-speed HTTP-based APIs like REST interfaces.
Client/server architectures can be built with the included SunRPC support. This is a very robust and mature implementation of this binary RPC protocol, both on the client and the server side. It is wire-compatible with C implementations of SunRPC. There is a generator for transforming SunRPC IDL files into Ocaml modules. Authentication and encryption are also supported (using GSS-API, or the non-standard SSL extension).
Compute jobs profit from Ocamlnet because the netmulticore library allows it to run compute tasks on as many cores of the machine as needed. The tasks can communicate with message passing and exchange data via shared memory. Of course, [netmulticore] is strictly typed.
Any kind of application can cherry-pick the parts of Ocamlnet that are considered useful. Especially, Ocamlnet includes a number of network clients (for HTTP, FTP, Telnet, SMTP, POP, LDAP), and a large number of network-related string processing functions (e.g. for URL's, Base64, UTF-8, mail headers). For interacting with the system there are functions to invoke subcommands (shell library), and also for globbing, sending email, and logging. Local and remote filesystems can be accessed with the Netfs framework. The netsys library wraps lots of additional system calls that are missing in the Ocaml standard library.