I went quite a while on my shaman without any class specific add-ons, but no longer. It all started as I got into instances more and more and found it a little cumbersome to pull up totems and put them back down.
I found myself wishing for a way to quickly put down the totems I had already chosen without thinking too much about it or having to click 4 different places. So I did some hunting for an add-on and found TotemTimers best matched what I was looking for.
I guess that is perhaps the best way to go about finding an add-on. Identify a need and look for something to fill that need. My usual approach to add-ons is I see or hear about a cool add-on then go an play with it. Most the time I end up discarding those.
I'm hoping one day I will identify a need and there won't be an add-on out there. That would give me the incentive to get into creating my own add-ons. Right now my lazy programmer nature prevents me from recreating the wheel.
I've added this add-on to the list of add-ons I use as well.