I have a copy of the Nero OEM suite (obtained legitimately, with my DVD burner), but I can't find the CD key/Serial no. for it (which I believe used to be on the envelope, which is... somewhere...). Is there a legal and legitimate way to obtain the CD key for it?

Call tech support?

Legal and legitimate? Buy a new copy.

If you have a receipt or some kind of Nero account, you might get lucky, but I think you're SOL.

Call tech support though, its worth a shot.

call the manufacturer, send copy of your COA and you will probably get a replacement.

ALSO-- if you have EVER registered the product, you can usually get your key or a new one from the manufacturer. I had to get copies of some really old 3rd party controls for development and upgrades, and LUCKILY many of them were "registered" by previous employees that were no longer with the company, but our company name was tied to them... I called about 15 companies and was able to get new ones reissued for most of them... It pays to register software, in most cases. (True story too!)

Wehn I ever I lost one in the past, there are plenty of ways of getting them on-line.

ww2.nero.com/enu/FAQ_Serial_Number_Where_To_Find_1.html

For OEM bundles, such as Yamaha, TDK, Memorex, Lite-On, etc. you do not need a serial number, as it is embedded and will install automatically. After a successful installation, you can find your serial number located in your registry.
Follow the steps below in order to locate it:
1) Click on ´Start --> Run´ and type in ´REGEDIT´.
2) Click on ´OK´, which opens the Registry Editor.
3) Click on the folders ´HKEY_LOCAL_MACHINE --> SOFTWARE --> AHEAD --> NERO BURNING-ROM --> INFO´.
4) You will see your serial number on the right-hand side of the Registry Editor, with following name (related to the respective version you have): Serial4, Serial5 or Serial6
This entry looks as follows:
14xx-xxxx-xxxx-xxxx-xxxx         (for Nero 4)
15xx-xxxx-xxxx-xxxx-xxxx-xxxx (for Nero 5)
1Axx-xxxx-xxxx-xxxx-xxxx-xxxx (for Nero 6 Ultra Edition)
Please note the number.

Quoted: For OEM bundles, such as Yamaha, TDK, Memorex, Lite-On, etc. you do not need a serial number, as it is embedded and will install automatically. After a successful installation, you can find your serial number located in your registry.

My Nero OEM that came with my Sony did not require a key for installation. Good thing too because I've had to reinstall at least 3 times.

I emailed Codemasters' customer support for my missing cd key, they said if I sent them a photo of the disc, they'd send me a code.  Turned out I didn't need to, Adamtheframer helped me out here.