Glyphs - Greater Glyph of Scaling Magic Resist: Pretty standard on most junglers. Very efficient runes in terms of stats and allows you to mitigate magic damage without having to spend much gold on magic resist.
Quints - Greater Quintessence of Movement Speed or Greater Quintessence of Gold: Player's preference, really. MS quints give some nice utility, though you already have Bloodboil to haste yourself faster than most champions and most Nunu junglers go for Mobility Boots for roaming purposes. Gold quints give you more income since you want to spend a lot of time ganking and counterjungling rather than straight-up clearing camps. I prefer the Gold quints on Nunu, personally.
I'd suggest the defensive Runes as well. I don't find Nunu has mana problems so I'd even suggest defensive Marks as well. Nunu can't really do much other than waddle around and throw snowballs, as well as get the occasional perfect Ultimate (in the brushes is best since the enemies can't see it channeling that way.) Thus, defense is your best friend, but to each his own. The real challenge of Nunu jungle is knowing your capabilities, and that you're better off supporting your team and trying to combo your CC with Allies', rather than being the frontline warrior like other jungles.
Seals -
Glyphs -
Quints -
For quintessences you can make a lot of things work however I like to run