Just thought of two things that could be good, doubt I'm the first though.

1. Applying redstone dust to a carpenter's block, just like you can apply glowstone and dyes, so you can make any block emit a signal (probably less than 15, to compensate not being a full block of redstone). Could be useful for hiding a redstone signal, I guess.
2. Being able to place carpenter's hatches in a way that makes them open inwards, like some sort of 1x1 door with the hinges on the top or bottom. While it wouldn't be too useful for letting someone pass through, it could be a nice way of hiding the controls of a machine or something without needing an entire door.

I like that suggestion, it adds a nice way to hide maintenance shafts if you use morph to get into tight spots. Also might be good for stuff like thaumcraft golems

The redstone dust idea really isn't gaining any traction. The single-high door has the code in place to happen, I just never got around to implementing it. But honestly, it's use would be so limited I'm not sure why time should be spent on it.