After one day of testing I think that such features are necessary:
1. Batch removal of products.
It is too difficult to delete products on per-product basis. There should be an option to check/uncheck them and delete with one click
2. Possibility to add more order statuses without changing it in DB
3. WYSIWYG editor for products and categories descriptions
I’ve spotted portions of TinyMCE code in many files. I hope that this editor will be in use in next releases
4. Bestsellers module
Please add features in this topic so that Varien has this in one place