As a few others have posted gog are currently offering a sale on selected games. Some that caught my eye include:
Arcanum: Of Steamworks and Magick Obscura - £1.19
Vanmpire The Masquerade Bloodlines - £3.99 (because its Activision probably the best price you'll get for this game)
Psychonauts - £0.79!
System Shock 1 and 2 - £1.19 each
Syberia 1 and 2 - £1.59 each
Grim Fandango Remastered - £1.99
These games should be in everyone's library. Period.