Add a refresh button
Since the introduction of Safari 4, I've been missing the dedicated Refresh button in the Toolbar. While there is one available at the end of the location bar, it's much smaller than it used to be and too close to other easy-to-hit targets. Fortunately, someone has taken advantage of the advent of extensions in Safari 5 to bring back the Refresh button.
To use it, you first need to enable Safari's developer mode: Go to Safari-> Preferences -> Advanced. Turn on Show Develop Menu in Menu Bar. You may need to relaunch Safari at this point.
From the new Develop menu, select Enable Extensions. Now go here and download and install the Safari Reload Button extension. That done, Control-click on the Safari toolbar (or go to the View menu) and choose Customize Toolbar. Add the new Refresh button wherever you want to put it.—Geobunny
[Editor's note: The "someone" who came up with this tool is none other than Ars Technica writer (and occasional Macworld contributor) John Siracusa. As several readers commented, you could just hit Command-R instead. But if your hand is on the mouse, or you're just more mouse-centric, this button could save you time.]
Get RSS instead of Reader
In previous editions of Safari, there has been an RSS icon in the right side of the address field; you could click on that to see and subscribe to the site's feed. But that's no longer the case in Safari 5 when you're on something like a blog. Instead of the RSS icon, you see the new Reader button. To get to a page's RSS feed instead of the Reader view, click and hold the mouse over the Reader icon; a menu will appear giving you a Show RSS option.—pepijndevos
Turn off private browsing
In Safari 4, the only way to toggle Private Browsing on and off was with the Safari -> Private Browsing menu selection. But in Safari 5, an icon now appears in the URL bar—similar to the RSS and Reader buttons—when Private Browsing is active. Click on that icon and a dialog will appear asking if you're sure you want to turn it off. Click OK, and it will be.—rab777hp