Keeping track of things when programming

In a vaguely similar vein to a blog post by Jason from 37signals last month, where he discussed (among other things) the technique of having events nearest to now in larger type than those further away (and therefore less urgent), I had an idea that would help me immensely (and I imagine others) when writing large web apps. I use Zend Studio for writing my PHP apps (and indeed for more general HTML/CSS writing), but there comes a stage in many projects where you find you have loads of files open at once, combined with the need to be switching between them often. Zend's ability to clone windows certainly helps, as you can have 3/4 files readily visible all at once for reference/editing (even duplicates of the same file for writing at one end and checking it matches stuff at the other). Even with this insanely useful functionality (I actually feel partially handicapped when forced to use an editor that doesn't offer it), there's still plenty of searching through the many tabs (currently 18 as I write) at the bottom of the window for the next file you need to edit. Anyway, at last I get to my idea: have recently-viewed/edited files (tabs) in scaling text sizes. For example, the last file you were viewing before the current one would have perhaps double-size text, with others scaling down to the standard font size as you go back through the view history. Expanding on this (as the above only really helps when you're switching repeatedly between the same 2/3 files), the ability to mark tabs with a colour and/or size permanently would help further for common files that you need to find regularly, but not necessarily in the back-and-forth fashion described above. For example, I could set my access class to be red, bold text at 1.3 times normal size, so when I need to check something in that class file, I can quickly scan for the big red tab rather than strain my eyes parsing across the tiny tabs looking for the word 'Access.php'. There are undoubtedly other areas of your standard IDE that could use a similar or related treatment, but I'll stick to the tabs for now.