These are the list of challenges to unlock the PRO versions of all the perks in COD Black Ops.
EDIT 7/11/2010 - I don't own the game at time of posting and I have it on good authority that some of these may be wrong...Maybe take it with a pinch of salt but you'll hopefully get the general idea
2nd Edit on 8/11/10 - corrected some errors in original (thanks to Psychic5)
Hope people find it useful:
Lightweight Challenges:
Escape death 5 times after being shot
Get 15 melee kills
Get 10 offense medals by killing ops near their objectives
Scavenger Challenges:
Get 5 kills without dying 5 times
Get 5 lethal grenade kills with resupplied grenades
Resupply 150 times with scavenger
Ghost Challenges:
Destroy 30 aircraft without killstreaks
Destroy 1 sentry gun
Kill 20 enemies while their spy plane or blackbird is up
Flak Jacket:
Plant or defuse 10 bombs in Demolition, Sabotage or S&D. (extra game types).
Survive 10 explosions
Throw back 5 enemy grenades
Hardline:
Earn 7 killstreaks in one match while using hardline.
Get 7 kills without dying in one match
Share 10 care packages with teammates
Hardened:
Get 10 kills through walls
Destroy 1 piece of enemy equipment through walls
Shoot 200 bullets into enemy aircraft
Scout:
Get 30 headshots
Get 50 one shot one kills
Get 50 kills with secondary weapons
Steady Aim:
Get 150 hip-fire kills
Melee two enermies consecutively within 5 seconds
Get 100 kills after sprinting
Sleight of Hand:
Get 150 kills while ADS
Reload and finish off the enemy you wounded 10 times (shoot, reload, kill X10)
Kill an enemy within 5 seconds of reloading 30 times
Warlord:
Get 25 frag or semtex kills
Get 5 multi-kills with grenades
Get 150 kills using guns with two attachments
Marathon:
Capture 15 flags
Get first blood 10 times
Run 26 miles using marathon
Ninja:
Get 5 backstabber medals
Plant the bomb 10 times in Demolition, Sabotage or S&D. (extra game modes).
Get 150 kills using the suppressor attachment
Second Chance:
Get 3 headshot kills in second chance
Get 20 kills in second chance
In second chance, kill the guy who downed you 5 times
Hacker:
Destroy 25 equipment or explosives using hacker
Kill an enemy with claymores or c4 25 times
Kill 25 enemies within jammer or motion sensor radius
Tactical Mask:
Kill 20 enemies that are stunned by your concussion grenade
Kill 20 flashbanged enemies by your flashbang
Kill 20 enemies poisoned by your nova gas