When you plan to visit Nazca lines ...don't forget that it's forbidden to walk alone in the desert without authorization and beeing with an official guide ...The best way to see everything there is to take a little plane flying upon the line ....not too expensive ...the other thing to do around Nazca is going into an orange Hacienda and taste there orange juices they're wonderfull and really cheap ! 

Nazca Lines are pretty amazing, not as big as you expect, but still amazing. Not too much to do in the touristy town of Nazca other than eat drink and souvenier shop, But you can go sandboarding on the nearby sand dunes. I think it is the Friendly Brothers or a name similar to that, they are in the guidebook and run good deals on both, and if you go with them they let you use the facilities of their hostel for the day. Especially good were you taking an overnight bus in and out. If possible, email them in advance because most flights depart early morning (maybe delayed if waiting for clouds to roll out.)

Visit the lines: formas de animales y una figura humana de la cual se dice que podria ser un astronauta

Don't visit the lines. Its quite expensive to take a flight up there and sometimes (at least in my case) you get stuck with a student pilot who is just learning how to fly and is sitting beside a what seems like a more experienced pilot, however their flying is terrible and makes you sick to your stomach.
At least don't pay more then $50 for the ticket.

After examining lots of other hostels we took the 3 stars hotel Don Agucho.
Big and nice rooms, a small swimming pool, big green garden full of flowers and some parrots!
A nice oasis in the desert... 1 room per night for two 25$ (2007)

Before taking from Nazca the bus to Cuzco be sure to take a travel sickness pill!
The altitude differences and curves give you otherwise a hard trip. (I vomitted all night long...)

Almost nothing to do or see here other than the Nazca lines and an ancient burial ground. Take a tour from a local Peruvian with a small prop plane. You will be amazed at the lines. The burial sites are also quite old and full of history that you can see and touch.

After you have seen the lines, the old irrigation system and the old cemetry (both a little outside the city) are really great but preferrable is to do them with a guide with can you explain a lot about them or the nasca lines too. Before taking a next bus, it can also be intresting to have a look at the plain prices from Nasca. For example a plain flight to arequipa was even less then a first class night bus towards it and saves you a lot of time and a rough night in a bus

The Nazca Lines are truly awesome. Best seen by air and well worth the expense.

do not get drunk before taking a flight to see the "Nazca Lines" your stomac will strongly regret it....