I have long wavy/somewhat curly hair and I want a new haircut. I really love Hermione's hairstyle in Half-Blood Prince:

Here is it straightend at the premiere
Entertainment Weekly Scans
a really good and helpful Video Tutorial of Hermione's hair by pursebuzz:

Curling iron she used:
Le Angelique Curling Iron- 190mm (3/4")  $69.95
In a world of advanced styling, Le Angelique delivers the ultimate hair curling iron for the easiest way to curl your hair. Advanced technology creates a lasting style, preserves moisture and leaves a glossy shine. This luxury ceramic curling iron can be used on all hair types and textures of hair. teflon coated barrel keeps hair healthy by reducing exposure to heat. Specially designed to create popular wave and curl styles.

* Maintains even heat while curling
* Extra long Teflon coated non-stick barrel
* Heavy duty long-life heating element
* Heat resistant safety glove provided for fast curling process without burning
* Comfortable easy grip handle
* Heavy duty 8-foot tangle-proof swivel cord
* Safety on/off switch with light indicator

The curlers she uses to hold the bottom curls look like plastic rollers that have a snap to place over the curl.  I assume that they are the same size as the curling iron used which is 3/4"

Diane Snap-On Rollers 3/4"12 pieces
Other Possible Hair Cuts: