Product Key Reader detects and lists the product keys for Windows and various other applications (potentially very useful if you've lost them and would like to reinstall).
The program is a little dated, unfortunately. It'll only detect the product keys for Windows XP and 7, for instance. It supports Photoshop only up to version CS2, and TuneUP Utilities support seems to have stopped with the 2010 edition.
Still, if you do have some of these older applications or games then Product Key Reader may be handy (and if you have Windows XP or 7 then you'll get that key, at least).
Whatever you're looking for, the program is certainly straightforward in operation. Click Scan and it quickly identifies and lists the product keys for any supported applications on your PC; click Save to save them as a CSV or TXT file, and, well, that's it.
And if you do need more then the authors do recommend you try a commercial product, Recover Keys, instead (it supports many more programs, and later versions, too). Read more on the Product Key Reader site.
Product Key Reader is quick, free and straightforward, but a lack of support for recent software means it's no longer as useful as it was.