I use mine mostly to go to my friends' profiles occasionally, see when they were last here and what they've posted recently. It's much faster than finding them in the alphabetical Member List and surer than looking through a bunch of threads for something they've posted.

Also, I confess, sometimes taking a look through my Friends List will remind me of someone I haven't looked in on for way too long.

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I've been known to warn people who ask to friend me, that I have my hands full neglecting the friends I already have.