Apple’s Contact’s application includes a helpful feature called “Smart Groups”, which work similarly to Smart Folders in OS X. With Smart Groups, you can quickly create folders on-the-fly based on specific bits of information.

Contacts smart filters

For instance, let’s say that you work at American Express in Chicago and want to put together a work softball team. In this case, you could create a Smart Group to include everyone whose e-mail address is americanexpress.com.

But in order to ensure that you don’t include people who work at other branches, you can then add an additional criteria: City is equal to Chicago. (City Is Chicago).

Click plus to add new criteria row

Now there are a few people whom you know hate softball and would not welcome receiving such an e-mail from you. You can exclude individuals from the group by using the Is Not condition. For example, I could add a new condition row to my group:

Email Is Not old_crabass@americanexpress.com (you can also use the Does Not Contain operator as well.

Exclude members from group

Quick Guide: To Create a Smart Group in Contacts

Select File > New Smart Group from the menu
Or
Press the ⌥ + ⌘ + N keyboard combination
Type a name for the new Smart Group in the box on top of the window.
Click the leftmost drop-down list in the first line and choose on which field you are going to filter (name, email, city, department, company, etc.)
Click the drop-down arrow in the center box in the first row and choose the operator you want to use (is, is not, contains, does not contain, is set, is not set, etc.).
In the last box of the first row, type in the criteria by which to filter (ie. email, person’s name, name of company, etc.).
To add another criteria row, click the + (plus) symbol and repeat steps 3-5.
To remove a criteria row, click the – (minus) symbol.
When finished, click OK
To modify a smart group, right-click the group and choose Edit Smart Group from the contextual menu.