Just a small addition, but one that I hope you find useful. Basically, there are three new smart group rules available to help you organize people even more:

1. Member of - this lets you create smart groups that take into account people's memberships. Yes, you can already filter by groups, but this enables you to create a smart group, for instance, of everyone who is a member of the men's group who is over 30.
   
2. Created within - this lets you add a rule which looks for people who have been created within the last X days
   
3. Updated within - this lets you add a rule which looks for people who have been updated within the last X days

And remember, these can be combined with other rules as well, so you can get very fine grained. Another example would be a smart group of people tagged with "visitor", not tagged with "followed up" and who have been added within the last 2 weeks, which will make it even easier to keep track of recent visitors who have not been followed up with yet. The possibilities are endless!