It seems like I venture on this quest every 3-4 months but always end up falling back on somewhat out-of-date alternatives that get me by. I'm always afraid of the one patch where it blows up and there will be no update to save the day.
Anyway, I currently have 3 timer bar groupings that I use:
1) Chronometer for spell/ability effects (DoT/totem timers, how long frost nova will keep them rooted, how long before MS wears off, etc)
2) Hourglass for spell/ability cooldowns (when my spells/trinkets/etc will be available to use again)
3) Antagonist for enemy cooldowns (when their spells will be available again, or wear off, such as when ice block or icey veins will fade)
I really rely heavily on these, especailly the first two (the last one not so much...mostly for PvP), and I'm seeking updated alternatives. I've updated my UI almost entirely with well-supported addons, and while those listed above receive fixes now and then, for the most part they seem abandoned (it looks like Durcyn has picked up Hourglass, but it's still in need of some polish...looking good though). Ideally it would be great if there were an all-in-one solution with customizable bar blocks, but I won't hold my breath ;) I thought NECB might fit that bill one day, but it's under new management now and isn't quite there. Thoughts?
I'm using Spellreminder for all my DOTs/Buffs (Slice and Dice, Rupture, Find Weakness, Poisons, etc.) it simply adds every buff/dot to a list, where you can decide which to show.
And CooldownWatch (http://wow.curse.com/downloads/details/11308/ ) for specific CDs (I'm a rogue, so i want to see CD of Drums, Cloak of Shadows, etc.).