In Safari, you can highlight text using traditional click-drag selection method. But there is one more way of highlighting text in Safari! Instead of a single-click to begin the highlighting, use a double-click, hold, then drag. As you drag on, Safari will highlight by word, not by a single character proximate to the cursor.
This makes selecting much easier and more accurate (assuming that you want to select words in their entirety).
[robg adds: This is actually a standard feature of Cocoa, and should work in any Cocoa application such as Mail and TextEdit. We have run a couple of other hints about Cocoa's text editing features (1, 2) if you'd like to read more about them.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030309014543351