See, I find iTunes' default font size uncomfortably small. That's in part due to my widescreen monitor, which runs at a fairly high resolution. Fortunately, I'm no longer squinting at my music library thanks to this simple fix:
1. Click Edit, Preferences.
2. In the General tab, set Source Text to Large.
3. In the same tab, set List Text to Large.
4. Click OK to close the Prefs window and implement your changes.
Presto! Now the text in the lefthand menu bar should be easier on the eyes. Same goes for the text displaying your song list. Sometimes the best hacks are the simplest.