Ever found it incredibly annoying when trying to add images into a list on the fly? (without having to go away and add them to a library first - then come back and manually add a reference).
Using SP2010's enhanced rich text field, you can upload and add an image directly into the list without having to leave the page.
When editing the enhanced rich text field (whether editing a single item in the edit form or using the cool new 'Inline Editing' feature (explained here), you have the option to insert from the 'Editing Tools' menu.
This brings up the 'Select Picture' dialog where you can select a local image to upload and a library to stored the uploaded copy.
Then save the uploaded image and complete any metadata requirements.
The image is inserted into the SP list but is managed centrally within the chosen library.
A very handy feature that was missing from 2007 and I'm glad it has been addressed in 2010.