I've decided that my BioCube needs a reboot, and since I know at least some of my relatives will give me cash for Christmas, I'm going to a LFS (possibly two) sometime in late December. Here's what I have to work with:

Not so good, huh? Kind of a mess.
One blue damsel (a peaceful type)
One Wheeler's (maybe) shrimpgoby
One tiger pistol shrimp
One rooster waspfish
One sand snail
A couple of bumblebee snails
A few dozen polyps of some sort
And about six large-ish aptasia that are going to die as soon as I can kill them.

What I plan to do:
Clean the glass so I can see. My dad found out that a disposable safety razor with the 'safety' bits pulled off works great on even the really stubborn algae.
Kill the aptasia. Interestingly, it would seem that waspfish are immune to the stings... My waspy just landed on one a minute ago. He sort of jerked away from it, but now he's just swimming around grabbing food, he doesn't look bothered at all.
Add more live rock and rearrange a few pieces that I already have to display things better and hopefully let me see the waspy more often. Don't worry, I won't move the base rock... I know that'd stir all sorts of stuff up, and plus it'd wreck the pistol's underground mansion.
Tug that poor half-hidden conch shell out of the corner, clean it off a little bit, and make it the centerpiece.
Add some coral frags. A store near us sells things like 5 or so mushroom corals or a little rock with zooanthids or other small, nano-sized frags for $5 each, which is what I'm planning to get... Mushrooms and other non-picky things.
Add a tuxedo urchin because they're neat and will clean the glass at least some.
Add a hermit crab or two for food-picking-up duty.
Add another sand snail to help stir sand.
Possibly add a seaweed-type thing to help clean the water.

What can a BioCube's original light support? The polyps (whatever they are) seem just fine, so I'm thinking maybe low-light things like 'shrooms, which is fine by me. And it can obviously support aptasia, but I suspect aptasia could grow by candlelight.
I'm planning to take the fish and snail out, possibly the pistol if I can, and put them in a little 1.2g tank while I'm rearranging. If they have a bit of rock in there with them and an itty-bitty air-powered filter or a bubbler, how long can they stay in there? Damsel is slightly over an inch long, goby is a bit under an inch and a half, waspy is about two inches. I doubt I can catch the pistol without tearing everything up.
Will injecting lemon juice into an aptasia's mouth via a non-needled syringe kill it? There's only six and they're all fairly large, I think I can do this with them all.
Fire shrimp; are these any danger to really small fish? I know they can kill other cleaner shrimp... I'm thinking of getting one.
I know green brittle stars will eat fish, but are there any large-ish brittles who won't kill my fish? It's the shrimpgoby I'm worried about. Also, I'm guessing the bio-load of a brittle star is fairly low... Right? Since they're mostly legs? I'm looking for something that'll hide in the rocks and stick a couple of legs out so I know where it is, something that can clean up for me and maybe replace the potentially coral-nibbling hermits.
Crinoid squat lobsters; how likely am I to actually see one? It doesn't have to be putting on a parade, I'd just like to be able to see one if I put it in. I know a place that sells some.