Plugin or Method to Exclude Post Content From Summary?

I’m a big user of the <!–more–> tag but there is quite a bit more I would exclude from the post summaries if I was able to.

I’m thinking something like <exclude>this content blah blah</exclude>

or even the opposite <summary></summary> wrapped around what one wants to appear in the post summary.

Anything out there like this? Seems pretty obvious, I’m sure someone’s thought of it and put out a plugin for it.