I see a lot of misinformation across MMA message boards in regards to professional boxing records of the fighters (such as always hearing that Davis had a much better boxing record than Lytle). Boxrec is a site that I've used long before Sherdog's fightfinder, and is essentially the same thing (with a much better layout) for boxing records.
Marcus Davis - Davis' Pro Boxing Record
Chris Lytle - Lytle's Pro Boxing Record
Nick Diaz - Diaz's Pro Boxing Record
KJ Noons - Noons' Pro Boxing Record
Denis Grachev - Grachev's Pro Boxing Record
If you know of any MMA fighters that have had some professional boxing experience, just input their name on boxrec.
Interesting side note - In Lytle's last pro boxing match in 05, he TKO'd a guy who went on to be the biggest challenge so far to top ranked and undefeated at 21-0, Jean Pascal, on ESPN's Friday Night Fights just 2 months ago.