There are just some tools that make life easier. Although I'm a self proclaimed CLI junkie, I think that adhering to fundamentalist attitudes only leads to atrophy. To that end, I'd like to suggest a couple of tools that I grudgingly have to admit are better than their command line equivalents. Its not these tools should be used without knowledge of their CLI counterparts; it's just that having graphical equivalents somehow refines their usage and reduces cognitive resistance when you're in the Flow.

Cornerstone

I can't say enough about Subversion, but trying to keep track of changes between commits and doing diff comparisons with your working set versus the last revision is nothing short of a PITA. Thankfully, there is mature, stable graphical Subversion client for OS X - Cornerstone. It does a great job of abstracting various Subversion operations and does not suffer from extreme featuritis. Give it a try if your tired of looking up man pages to get just the right svn syntax.

Araxis Merge

While diffing files is old hat, the output is just barely human readable. Too much effort is expended by the user trying to visually grep the output. They say a picture is worth a thousand words, in the in spirit of "Ut pictura poesis" I would have to agree when using a visual diff tool. Having side by side comparisons greatly improves the ability to use diffs in a more coherent manner. Thankfully, Araxis has ported their flagship Merge tool to OS X. Like Cornerstone, the features are implemented with minimal clutter. This allows it to integrate cleanly into an XCode based work flow. With its seemless integration with Cornerstone, checking working copy diffs to a source code repository can't get any easier.

O'Reilly Safari

Do your self a favor and forget the forest of books that inevitably become obsolete and sign up for a Safari subscription. Technical books have a limited shelf life. Prevent become antiquated and get the latest documentation without the hassle of having to lug around a dead tree. It's not that I don't like physical books, but the rate at which technical documentation evolves makes it unrealistic to have a well stocked reference library without having to spend a fortune. Combined with the BookBag iPhone app, you can have your cake and eat it too.