Here is a list of resources that I find very useful.
Quicksilver: My favorite Mac OS app. It's like Spotlight but on steroids
The Silver Searcher: Tool to search content of files (a la grep)
MacTeX: A distribution of software and packages for LaTeX on Mac. Contains some great softwares:
ADS to BibDesk: A great AppleScript which allows to add ADS and ArXiV papers to BibDesk using a simple shortcut. Can use a proxy computer in order to download papers as if one is on their university network.