A collection of quick horse sketches in pen:

Here's a few more quick bird sketches:

More creeping things:

Some simple pen sketches:

A few more quick pen sketches:

Some pen portraits:

Here's a few more quick pen sketches. Various, mainly horses;

Some more quick pen sketches:

Here are a few more quick pen sketches:

A few 30 second pen drawings from www.posemaniacs.com:

A few quick equine sketches:

 Two minute fish sketches:

Here's a few quick pen skeches:

A few more random sketches: