Hi! I don't think I've seen an exercise tutorial only targeting barre chords like you mention, but it's not a bad idea!

You can try these exercises though, where you go through all chords while staying in one position on the neck. This forces you to practice all kinds of different chord shapes and ultimately strengthening every muscle in your fretting hand.

http://www.guitartricks.com/lesson.php?input=18125&s_id=1391

Also, you can modify this exercise and do it while holding down a barre the entire time:

http://www.guitartricks.com/lesson.php?input=14212&s_id=915