we made a big mistake by thinking we could start at one end and walk the base of the cliff to scout the routes we wanted to climb. In doing this we headed for Mt Nemo North. Big mistake! This end of the cliff sees little traffic. Most of the routes at this end are on chossy broken limestone with sport routes few in between. Avoid going to Nemo North. Instead, take the main trail that goes to the Main Lookout. There is an easy descent just left of the main lookout. Here you will find much better walls and quality routes.
If there's one crag I really know, it's Nemo. Fred's right that you can't walk from Nemo South to Nemo North along the base; you need to walk along the Bruce trail at the top of the crag. However, Fred is wrong about Nemo North: some of the crags best sport routes are there: the Graduate, High Society, Trajectissima--these are fantastic, classic Escarpment lines. Many of the routes are mixed, but that's Escarpment style (easy, well protected cruising to harder faces). There are also some really stellar crack problems and mega-classic trad lines: Camel, Cat's Tail, etc.
Beware that the guide book is worse for Nemo than it is for Lion's Head (and that's saying something).
Other great Nemo sport routes:
Train in Vain (mixed)
Fear and Loathing (mixed)
Suplex (mixed)
Seventh Origin of Alfred (mixed)
Scarface
Mean Streaks
Tendenitis
I Owe A Lot of Money to a Man Named Guido (mixed)
Big O Tree
Lost In the Forest
A nameless line just to the south of Female Belay Slave (great warm-up before the Graduate)