We've been polishing up a cool new 1.6 feature over the past few days - and I got pretty excited seeing it working with a real set of data. The feature is Batch Update Via Profile. It allows you to define a profile with (almost) any standard and custom fields and use that to display a table for updating many contacts at once.
For example, if you want input hard-copy responses from a mailer for a group of contacts...You could define a profile with the fields you want to update. Then use Find Contacts to retrieve contacts in the group and select "Batch Update via Profile" from the -actions- drop-down menu. You then get a table with a row for each contact in the group and the fields you've selected for updated. Update some or all of them and click "Update" - and your changes are saved.