All Powers + 15K Bonus XP In Post Game
Complete the story twice, once with the Hero route and a second time as Infamous or vice versa. After the second play through, after the credits end, a message will come up as the post game becomes available that will say that you have completed both paths in Infamous 2 and have unlocked access to the opposite Karma powers of your current Cole along with the powers of the character you didn't transfer with, you are also granted 15,000 XP to help with paying for them for some extra post game fun.
Early Access To Flood Town
Go into your mission editor and move your marker to either bridge that connects the first half of New Marais to Flood Town. Raise the marker so that it's at least a good 50 feet higher than the raised bridge. Now exit your mission editor and Cole will instantly appear where your marker was when you exited. You should be able to use your thrusters and clear the gap between the raised bridge and into Flood Town.
Start a blank mission in the UGC Editor. Move your marker to a location. Exit the editor without saving (press X) and Cole will appear in that location.
Infinite Energy Via Body Batteries
You need 'Evil Karma' for this. Equip your Alpha Bolt and repeatedly shoot a body until it glows blue/red with electricity, then drain for an energy boost. You can repeat this for infinite energy.
Red Ring Zinger
In New Marais there is a store called Red Ring electronics repair, with a flashing red neon sign that resembles a dead Xbox 360 light.
Repeatable 100 XP
After you use the transfer device in the story mission Storm the Fort, you'll get a bonus for 100 XP. If you kill yourself using the deep water to your left, you'll respawn at the same point and get the 100 XP. You can repeat this as many times as you like.
Open the UGC editor, and mouse over the location on the map that you would like to teleport to. Quit the editor (make sure you do not save the level) and you will appear at the location.
Video Game References On Theater Signs
On the Hush Theater in New Marais, the movie board has some titles. The titles are all parodies of real video games.
Assassin's Need is a parody of the Assassin's Creed series.
Call of Booty is a parody of Call of Duty series.
Epic Hickey is a parody of Epic Mickey.
Hey, Low Reach is a parody of Halo Reach.
Latch it and Skank spoofs Ratchet and Clank.
Little Big Unit is a parody of Little Big Planet.
No Need for Speed is a parody of the Need for Speed series.
SLY is a parody of SuckerPunch's own Sly Cooper series.
Solid Serpent The man, The Movie is a parody of Metal Gear Solid series.
Uncharted Love is a parody of the Uncharted series.
Zeke And The Thievius Raccoonus
In one of the cut scenes you approach Zeke reading a book. If you can spot the title you can see he's reading 'Thievius Raccoonus.' This is a reference to the Sucker Punch game Sly Cooper and the Thievius Raccoonus.