Short, styled, messy with highlights. Ryan Seacrest started this do. It is an easy to maintain look and had its starts with alternative rock bands whom have taken it to more extremes (spikes, different colors, etc...) This is a very easy hairstyle to manage. Just use hair spray, mousse whatever and twist a little here and pull a little there. Some women are also using this for short styles. This easy, messy do is here to stay.
The short business cut. This has always been in. Everyone from George Bush and Jeff Gordon to Jay Leno sport this one. It can be parted to either side, brushed back or down. There are many variations. Sometimes it even looks like a bowl cut - popularized in the days of Leave it to Beaver, the Beverly Hill Billies, Green Acres and other shows that highlighted inbreeding in society.
The mullet. This big hair style of the 80's is actually making a comeback. Wrestlers, country singers, even want to-be stars like Kevin Federline have been seen wearing mullets. The mullet originated with car salesmen in the 1970's. It was a fun, easy do that was business in the front and party in the back. They could tie it in a pony tail and keep it under wraps at work and then let it out for partying. There are many variations even including the rat tail (hopefully this won't come back). There isn't much care needed for a mullet. What would George Bush, Dr. Phil, Ryan Seacrest, or even Simon Cowell look like with a mullet? I bet ratings for American Idol would double.
The medium-long cut. Basically this is where the hair is about 3-4 inches long across the top and shortened as it comes don the back to about 1-2 inches. One just puts moose or gel in it and works it in and then comes their hair back with their fingers. This is a cut primarily for those with wavy hair as it will show off and glamorize your curls. This is a star favorite - Antonio Banderas and Tom Cruise have sported this do several times throughout their careers.