One of the biggest trends in network-enabling embedded systems is the inclusion of a web (HTTP) server. The added HTTP server can then be used for enabling remote administration or remote data viewing. In the case of my SYSM module, for example, the HTTP server enables my users to configure and monitor various aspects of the control system.
Though the open source Apache HTTP server is the most widely used HTTP server in the world, it is not necessarily fit for embedded systems. Mainly, it is very difficult to cross-compile and tends to be rather large in terms of required storage space. There are, nevertheless, other open source HTTP servers that are much more adapted to embedded systems. In particular, Boa and thttpd are small, lightweight, fast servers and are a perfect fit for embedded Linux systems.
There does not seem to be a clear set of characteristics to help in choosing between Boa and thttpd. The only really notable difference is that Boa is distributed under the terms of the GPL while thttpd is distributed under the terms of a BSD-like license. The size of the resulting binaries are, however, quite comparable. Both packages also support CGI scripting. Therefore, I suggest you have a look at both to decide which one you prefer.
Boa is available from http://www.boa.org/ and is distributed under the terms of the GPL. Boa requires only a C library and can be compiled both against glibc and uClibc. For my SYSM module, I used ...