PC (and now Mac!) digital download service Steam has kicked off a site-wide sale offering big discounts on everything from AAA to indie, including bundles like the ‘Northern Lights’ pack (above) — which includes Crayon Physics, the aforementioned Saira and the excellent UK indie Plain Sight — and the Best of the Underground pack.
Also of note, all the games from Darwinia creators Introversion are bundled for $5, and even recent releases like BioShock 2 and Borderlands are around half off (and available in their own 2K bundle).
The Steam store site has the full listing of discounted items, which remain on sale until July 4.