Filter posts in admin & RSS for IM clients

Hi,
At some point, I temporarily failed to include a specific tag for some of my posts. This evening I had to manually go through to find the posts (out of more than 700) where I hadn’t included that tag. It would be great to have an option in the edit posts dialog to show those that DON’T contain a particular TAG. Also the ability to filter by tag would be great.

Finally, rasasa was a wonderful platform for enabling the subscribing to feeds in one’s IM client. I would LOVE to be able to offer that feature to readers of my blogs – as an integrated feature through wordpress.
Thanks,
Sue