tex-numbers provides an interface for retrieving label numbers from tex documents and uses this to augment some features of AUCTeX (previews, folds, ...) with correct numbering.

tex-continuous provides a minor mode in which a tex document is compiled continuously using latexmk, the error log is parsed using AUCTeX, and errors are reported via flymake.

preview-auto provides a minor mode in which AUCTeX previews generate automatically in the visible part of the buffer.

I've shared these primarily via word-of-mouth to colleagues, and have received positive feedback.  Any other feedback or suggestions would be welcome.

Thanks, best,

Paul