Here is my contribution. Sugarphreak did one on CAI's so that's why they aren't in my write up:
Short Ram Intake Systems
Short ram intake systems are slotted in between cold air intakes and chambered intakes. Short ram intakes and cold air intakes use similar if not the same type of tubing to help increase the flow of air into the engine. However, short ram intakes like the name suggests is shorter and located inside the engine bay like chambered intakes. This allows for a simple installation and easy filter cleaning when necessary. It does not give as much response as chambered intakes, but is a good alternative to chambered intakes if you have an AT Fit or aren't willing to tinker with a cold air intake. To date, there are two types of short ram intakes for the Fit not including cheap eBay ones.
Fujita Short Ram Intake
The Fujita Short Ram Intake is similar to the Fujita Cold Air Intake, but located within the engine bay. Fits both MT and AT Fit's.
~3.8BHP gain and ~4.3ft/lb Torque.
Injen Short Ram Intake
The Injen Short Ram Intake is actually converted from the Cold Air Intake. No picture could be found. Gains are ~3.3BHP and ~3.4ft/lb Torque.
Chambered Intake Systems
Chambered intake systems are similar to short ram intakes, however they contain a chamber instead of straight piping. Chamber intakes provide better throttle response and more low end power. However, it does sacrifice a little top end power. A positive of chambered intakes over cold air intakes is that the filter is located inside the engine bay. This provides easy access to the filter for cleaning and prevents the filter from getting dirty in less than nominal conditions. Also, chambered intakes can be used in AT cars and MT cars alike. On the negative side, chambered intakes usually absorb warmer air since it is located in the engine bay. Currently there are 3 chambered intakes on the market.
T1R B-Max Carbon Intake
By far the most popular chambered intake around. Produced by AJ Racing out in Vancouver, Canada, many Fit's are currently running this intake.
5.3BHP gain and 5.09lb/ft Torque.
Last Station Power Box
Very similar to the T1R B-max Intake. No information regarding the gains, but expect it to be similar to the T1R values above.
Mishimoto Intake System
Brand spanking new on the market, no results to speak of yet. Cheapest of the three chambered intakes.
Other Intakes
J's Racing Tsuchinoko Intake
The fabled J's Racing Tsuchinoko Intake. Recently developed by J's Racing straight from the land of the rising sun, Modifications were needed to adapt the JDM version of the intake to fit the USDM Fit. Currently, there are only 4 USDM Tsuchinoko Intakes, one of which is pictured below and is the final product after development with AJ Racing. The other 3 intakes have recently arrived at AJ Racing and have already been spoken for. Don't expect to see too many of these in NA Fits as they are extremely pricey, up to 2x-3x as much as a CAI, SRI, or Chambered Intake. However, this intake provides the most gains throughout the power band. It is basically a combination of a chambered intake and a cold air intake made of carbon fiber. As quoted from AJ Racing: "One of the hardest part was the intake. The Tsuchinoko (susage) portion fitted with no problems but the sensor hole and cold air portion's fitment were way off so J's Racing made adjustment for USDM Fitment...They finally got that done but it took them almost 3 months to do..."
*Photos were taken from manufacturers website or from Fitfreak.net from forum members*