Colorado Springs by ltlj, Retrograde universe, prequel to Vegas - it's tense, and despite knowing how everything turns out in Vegas, totally works the suspense beautifully.
Entire series can be found at the main page, Retrograde. Counting at six stories in the main series, three Retrograde-verse outside the main storyline, and two snippets. And pretty much the one thing I'd take to my desert island to introduce the natives to the wonder of sci-fi and SGA. See my earlier wild numbered flailing here for--um, wild flailing. With numbers.
Seriously, unless you are on that island (I'll be there soon! With DVDs!) then you *have* to read this. If you already read it, I think a re-read is in order.
Um. I'm a *tiny* bit infatuated with this universe.