I use Tactor’s (http://onflapp.wordpress.com/tactor/) regexp functionality to expand my custom text macros. For for example, I can define something simple like MYEMAIL => tom@foobar.com. However regexp allows me to do more interesting things as well, like creating links: wiki:MyDocumentation => http://pages.intranet.com/docstore?page=MyDocumetation?view=html.
– lauch Tactor (it is free app)
– go to preferences -> regexp
– add regexp
you can use capture groups here, e.g. wiki:(w+)
– set the ‘matched key’ to ACT_TEXT – this will place the result into the clipboard
– set the ‘matched key’ to what the resulting text should be like
you can use the regexp substitution here, e.g. http://foobae/$1
– expanding is done by selecting the text macro in a text (any text field should work) and choosing ‘Expand Selected Text’ from the top bar menu.
This method is kind of technical to setup but very powerful. If one is not afraid of a bit of programming, it is possible to …

Source: Mac OSX Hints