Since I don't do CGIs if I can help it, Perl's capabilities in that realm are irrelevant to me.

However, Perl is a good general-purpose language. It's also fun to do language experimentation (see Class::Prototyped for example).

I have an article coming out in Embedded Linux Journal that describes a data acquisition system for scientists in the field; this embedded system uses Perl for its data acquisition, queries, network connectivity, administration (via Webmin), etc. One thing that made Perl better than (say) C in this system was eval "string": to add a new kind of data channel to the system you give the system a small chunk of Perl code that acts as glue between the data acquisition scheduler and the particular sensor or computation you're logging. These can get added at runtime without bringing down the system, without explicit compilation, and they're typically only a few lines.

Though there were a few CGIs in the system (for configuration), the bulk of the work was done by Event.pm and BerkeleyDB.