GlassFrog has a simple way for you to access the email addresses of all the members of a circle or the whole organization.  

Organization Member List

 To send messages to all or certain subcategories of users in your organization. Click the "Membership Lists" link in the Reports menu.

This will display a page listing several reports:

From here, the Email button will open your default browser. Right click it to access browser options for copying the email list to your clipboard (see Option 2 below). Alternatively, you can download the email list as a comma delimited list (.csv) file.

Circle Member List

Navigate to a circle page, then the Members tab.  Click the Email Core Members button to open your default mail browser.  Alternatively, in most browsers you can right click this icon and copy the email addresses to your clipboard.  

Option 1:
  Open default mail browser

Option 2: Copy Email Addresses

Note:  If you are using Outlook you may need to edit your configuration to allow for the use of commas to separate email addresses.  See this FAQ for more information.