However, keep in mind that if you include too much, you run the risk of it all being ignored. That said, the presentation of the CD itself is probably the most important element of your package. That doesn't mean you have to have spent thousands of dollars on your presentation, a huge CD insert, a gorgeous color cover, etc. Some of the packages that impress me the most are the ones that have an actual design in mind carried through from the CD to the stationery the cover letter is printed on and further. If you're not getting a professional printing of anything, a color inkjet printer creating your own letterhead along with a similarly designed CD covering sticker, will work quite nicely.
Simplicity is often the best way to go.
Above all, avoid sending in a blank, recordable CD with black marker written on it. I know what you're thinking. The CD might become separated from the rest of your package and for that reason, you want it to be able to stand on its own as a professional piece of work, whether it retains its case or not. You want the reviewer to be able to contact you from that CD alone. Keep in mind that if your CD itself is a nice little package all on its own including inserts, you may not need the bio or the reviews and could probably get away with just sending in the CD and a cover letter.