The word "conlang" is short for "(artificially) constructed language",
the product of an unusual (?) hobby born from an interest in language learning.
To convince yourself that conlanging is not so odd a hobby as one might
think, please read on!
Language construction kit:
A fine tutorial on what it takes to create a conlang; indispensible if
you are new to the field
Conlang index:
An extensive link to conlangs on the web.