If you ask any PC gamer what the best platform for buying and downloading videogames is, almost every single one will tell you "Steam". However, up until now that pleasure has been limited to PCs.
That's set to change on 12 May, which is the date when Valve's software will take the leap to Macs, offering native gaming without the need to switch into Windows whenever you need a quick blast of TF2 or Left 4 Dead. The release was originally set for April, but delayed for undisclosed reasons.
Mac gamers will share servers and lobbies with their Windows-using friends, and Valve has confirmed that new titles will be made available at approximately the same time as the PC versions - there shouldn't be any major delays for porting games to OS X. Best of all, any games you've bought on Steam on Windows will be granted to you free on Mac.
You're still going to need to buy a mouse with more than one button, though.