Perl is widely used for applications development. Perl 5's modular, object-oriented approach provides for cleaner software design and better maintainability.
Perl also interfaces happily with database servers and other information sources. The DBI module provides seamless access to everything from Oracle to Postgres - and much more in between.
Perl/Tk can be used to build graphical interfaces to Perl programs which will run under the X windowing system. There are also other modules which can be used for graphics programming.