It is important to respect that your meeting is probably not the only meeting of the day for some attendees.  With this in mind it is a good idea to keep to time and close the meeting at the expected time.  If certain members of the group are able to stay on to finish a particular discussion then you should acknowledge the agreed time to finish and ensure that those people who have to leave are happy for the remaining group to continue conversations. The ideal would be to manage time effectively throughout the meeting to ensure that you don't have to over-run and everyone can leave on time. 

At the end of a meeting you should leave yourself enough time to review actions and assignments, and set the time for the next meeting.  If you put this as an agenda item it will help you protect the time for it but also alert people to bring their diaries so you can fix the date for the next meeting.

You should also give an indication to the group of when the minutes will be circulated to help them with planning their workload.

Finally, always try to finish the meeting on a positive note as this will ensure people come to your next meeting!

Downloads:

Managing Meetings.pdf

A guide to managing meetings.

Planning a Great Meeting.pdf

How to plan for a good meeting.