If you are interested in keeping track of what another member of the community is doing but are either waiting for a response to a friend request or don't want to request friendship, you can instead just Follow him/her.
When you follow a user, the user's activity displays under the People & Groups tab on the Activity List widget and no other widgets. The followed user will also receive an email notification that you are now following them.
If the person you're following is also interested in tracking your activity, he/she can either add you as a friend (to acknowledge the connection to the community) or follow you as well.
You can still have a user as a friend but not follow him/her by clicking Stop Following. This may be useful if you wish to remain connected to the person, but have found them too noisy to follow. You might also wish to remove him/her as a friend. Note: Users do not have the ability to stop other users from following them, and in a sense it's not necessary to have this ability. The user who follows you only has permission to view public actions - as with Twitter.
To follow a community member:
Navigate to his/her profile by clicking on anywhere his/her name appears (activity stream, forum post, blog comment, etc.).
Click Follow. The text changes to Stop Following which you can click any time to stop seeing activities from this community member.