Dia is designed to be much like the commercial Windows program 'Visio'. It can be used to draw many different kinds of diagrams. It currently has special objects to help draw entity relationship diagrams, UML diagrams, flowcharts, network diagrams, and simple circuits. It is also possible to add support for new shapes by writing simple XML files, using a subset of SVG to draw the shape.
It can load and save diagrams to a custom XML format (gzipped by default, to save space), can export diagrams to EPS or SVG formats and can print diagrams (including ones that span multiple pages).
There are also tons of extensions and third-party apps in connection with Dia - there are code structure generators, database structure-to-diagram interfaces and a lot more - don't be shy, go and explore!
The Regex Coach enables you to try out the behaviour of Perl's regular expression operators (namely m//, s///, and split) interactively and in "real time", i.e. as soon as you make changes somewhere the results are instantly displayed. You can also query the regex engine about selected parts of your regular expression and watch how it parses your input.
Of course, this application should also be useful to programmers using Perl-compatible regex toolkits like PCRE (which is used by projects like Python, Apache, and PHP) or CL-PPCRE. Also, Java's regular expressions and those of XML Schema are very similar to Perl's.
The regular expression editor is a module allowing you to test your PCRE with PHP in a very efficient way. It wraps preg_match, preg_match_all, preg_replace and preg_quote functions, and offer a visual GUI where you can tweak your regular expression easily.