Yeah, I'm not a fan of the MAME32 screenies either. The *NEW* ones (as of a few packs ago) are borderless, so thank goodness for that. That still doesn't fix some of the older ones.
Crashtest announced about 4 months back that the screengrab thing took too much time out of his already busy schedule, so he was calling it quits for a bit. To be honest, he put a bucketload of work into those. Every single "u" release he would get the changelogs, and go through every single original and clone that had changed, play test the game, and screengrab it somewhere interesting (not just boring demo grabs), as well as do a title grab too. Again, not just originals, but every single clone too! Unique screenies for well over 5000 titles!
Consider the sheer volume of games that have changed in just the 0.80-0.90 era, and that's a huge amount of work. So kudos to Crashtest for sticking around as long as he did.