As well as the STALKER for £3.50 deal I've spotted two more East India Company - A port royal style age of sail trading/privateering type game - is available for what I think is a mistake of £6.99 (I say it must be a mistake because it says 60% off, but 60% off £24.99 does not make £6.99) Witcher enchanced edition - Most will probably know of this, one of the best RPGs of 2007 - available for £11.49 I was very tempted by both, I already own the regular witcher but I can't install the enchanced stuff due to some registration issue and not having to deal with CDs and stuff with steam was tempting. EIC was tempting at the low price of 7 quid but I thought I have enough games to sink my teeth into right now.
Massive Team Fortress 2 Halloween deal: http://store.steampowered.com/app/440/ £2.50 for TF2, bargain!