One of the things I want to learn to do is play an open G with fingers 2-4 instead of my normal 1-3. I'm fighting almost 45 years of muscle memory, but I'm working on it.
OK, rarely, but I'll get there one day.
Anyway, one of the reasons the 2-4 fingering would be handy is that it frees the index finger up to play around with the D, G and B strings to add some flair to the G chord. One of those "flairs" is a Gsus4, which I find I'd like to have available.
(I also know about fingers 2-4 being handy for quicker changes to G7 and C, but that's a different topic.)
Back to our story: I realized that even playing an open G with fingers 1-3, I can move my index from A(fret 2) to B(fret 1), and mute the A with the pad of my middle finger (still on low E 3rd fret) and play: 3x0013. Voila! A Gsus4.
[For those of you who read this and said: "Well, duh!", forgive me. I'm a little slow on the uptake sometimes. ]
The moral is: if you need a chord, experiment. You can find a way to play it. "If it sounds good, it is good." - Topdown.