Q:

What can I use for schach?

What materials can be used for the top of a Sukkah?

A:

Anything that grows from the ground
  and is not 'mekabel tumah' is a
  candidate for scach[sic]. 

These are two of the three basic requirements. The last is that the material not be currently attached to the ground. This disqualifies, for example, building a suka next to a vineyard and stretching some vines (which fill the other two criteria) over as the covering.
By the way, according to many opinions, even non-wide processed wood (e.g. firring strips) may be used, provided there is sufficient spacing between them. 

A:

Trees branches and bamboo poles are popular.  I most prefer evergreen tree branches because they look the prettiest and may even have a nice aroma.  Anything that grows from the ground and is not 'mekabel tumah' is a candidate for scach.  Fruit is an example of an item that is 'mekabel tumah.'
mekabel tumah = something that can become ritually impure

A:

To tie the schach in place, many people/places use plastic cable ties, as they're not "mekabel tumah."  Some rabbis consider this not the preferred way, as the tie-downs should ideally also be plant matter.

