When work becomes overwhelming, a game such as WoW provides a much-needed escape. I delight in the simple things, and enjoy a small change-up now and again to keep things fresh.
Last week, installing BloodyScreen did this for me. A very simple mod, it does nothing more than splatter your screen with blood on a crit.
Really, it's the simple things. It works on spells, it works in melee, and it's actually got quite a bit of customization available. Once you log in after installing the mod, just type /bs and it'll bring up the main menu panel; from there, I suggest resizing the drawing area where the mod is allowed to put splatters on your screen, and then setting up the individual preferences in regards to splat size and what numbers trigger it.
Above are my own preferences. I set the splatters to fade individually after 4 seconds as well, and then had each character run a 100-hit average via the mod to set the threshold on the crit numbers:
My rogue and feral see quite a few more splatters than I do as a resto druid, naturally, as HoTs don't really crit (yet). I haven't found it to be obtrusive, and honestly, whenever I see a little splatter from a moonfire crit as I'm bouncing around trash, it makes me grin like the silly (and possibly sadistic) girl at heart that I am.
Just make sure you don't choose conflicting red-splatter power auras graphics without giving them a noticeable animation to make them show over this mod ;)