**THIS IS MY FIRST BUILD SO SORRY FOR THE LACK OF DEPTH**
So I was playing a bot game and was messing around and thought "im gonna try ad nunu for fun"
You can catch up with the combined mvmt speed increase and ice blast (and with flash).
Not much game tactic to be explained, just play like any other melee ad carry.

Make sure to keep blood boil up on him at all times during fights.

Pros:
Pretty much non stop cc (ice blast)
Base D on spells is already high (especially ult)
Pretty much non stop attack speed/movement speed buff
Nice little heal when around minions
Cons:
A little squishy if not played right
NOT RECOMMENDED IF BEHIND IN GAME
Not sure as to where he would be effective lane-wise at the moment. Solo top? Mid?

I chose to get 2 blood thirsters because nunu has a constant attack speed increase and it works well with the lifesteal. Also, the youmutsu's ghostblade is a nice extra buff on top of the already constant buff nunu has. Depending on the enemy team's cc you can replace berserk's greaves with mercury treads.

Flash: Utility, and good to close the gap for ice blast
Ignite: For the last extra dot
ALTERNATIVE SUMMONER SPELLS
Teleport: Viable for the movement across the map
Smite: If you're jungling
NOT RECOMMENDED
Ghost: You already have a movement speed increase from your 'w' and Youmutsu's Ghostblade
Exhaust: You have a 3 second slow with Ice Blast