I just got this game so this is of some interest to me, but D3PA just released a fairly official walk-through with info on all the goodies to be found in the game.

Just in time for the weekend, D3PA has released their official Dark Sector: Walkthrough
Guide. This guide contains exclusive tips, strategies and item pick-ups for players
to successfully complete Dark Sector. As you know, if you or your readers have
not yet finished Dark Sector, the information included in this walkthrough may
contain spoilers.

This is actually a bit of astro-turfing by Digital Extremes, but it might be better than GameFAQs.