The computer can tell me which applications are Intel-only, which are Universal (compiled for both PowerPC and Intel machines), and which are PowerPC only and thus won't run in Lion. (It also lists Classic applications, written for Mac OS 9 and earlier OSes, which still ran in Classic mode on PowerPC Macs.)
I have quite a few of all of the above, partly because one of the things on my work hard drive is a mirror of the old "Public AppleShare Server" that CIT used to run, offering freeware to campus.
Some of the applications I won't be able to run after I install Lion are some real gems I'd forgotten all about, including iPulse, a tiny tool that offers a graphical display of what your computer's up to, how much memory remains, and so on. I downloaded the 2009 version, and it turns out the serial number I got in 2002 still works on the latest version! I also discovered Art Directors Toolkit, a tool that lets you pick a color to see the RGB values or hex values needed for web page editing. It also calculates text sizes, scales, and fractions for you. A new version is $20, but I may e-mail to see if they offer free upgrades.
MoosePad was a friendly little notepad editor published by my friend Tom Clodfelter, and released as freeware after he had a stroke a couple of years ago. I've updated my copy, though I hardly ever use it. Nice to have a replacement for the venerable Note Pad desk accessory from the early Mac days. Doesn't look like there's a replacement for The Moose's Apprentice, a tiny utility for tweaking the configuration files at the core of the Mac OS.
Microsoft Office 2004? I don't know about "gem," but it created a lot with me. It's been supplanted by the 2008 and 2011 versions, both of which I have installed. I was keeping it for testing purposes, but since I won't be able to launch it any more, out it goes.
I only have a little over a decade of software on this Mac -- there are just a handful of old Classic applications from '97 to '99 -- but it's a good cross-section of the remarkable array of creative tools developed by fellow Mac users over the years.
One of the things that really struck me in writing my tribute to Steve Jobs was that, considering how long the Mac's lifespan has been, the Apple ][ era was awfully short: from April 1977 to January 1984. In a sense, that first Mac may bear more resemblance to the 1997 Apple ][ than it does to my MacBook Pro, or the iPad that evolved from the Mac OS. Tomorrow, I'll have a phone in my pocket that I can talk to. Welcome to the future.