Here are the ones that I know about and aren't self-explanatory.
Row 2, Column 2: Bridget from the Guilty Gear, he's a crossdressing boy who looks so girlish that the running gag is that "everybody is gay for Bridget"
R2, C3: Background art is from "The Scream"
R2, C7: /b/ is another sub-channel of /4chan, I think.
R2, C9: "Caturday" is a /4chan theme day where everybody is required to post cat macros.
R3, C6: "Do a barrel roll" is the advice given to you in Starfox 64 on the first stage when you're being shot at.
R3, C7: "Do not want" is the literal translation of Darth Vader's "NOOOOOO!" scream at the end of "Revenge of the Sith", which became "Backstroke of the West" due to some bootlegger's poor command of English.
R3, C9: The challenge to Dracula is the recurring theme of Alucard (Dracula's half-human son), a character from the Castlevania series.
R3, C10: Another Castlevania quote.
R3, C11: One of the Belmonts, a family of vampire hunters from the Castlevania series.
R4, C1: "Crawling in my skin" is the first bit of "Crawlin" by Linkin Park
R4, C3: "Fap" is the sound effect associated with masturbation in the webcomic "Sexy Losers" (I think)
R4, C8: Catgirls in anime are generally associated with free-willed, scantily clad characters that don't mind draping themselves all over the main character.
R4, C9: "Gaia" is a reference to an online RP community, Wiki it for yourself.
R4, C10: A play on the ode to Gaston song in Beauty and the Beast.
R4, C12: The most common pose that Ikari Gendo struck in Neon Genesis Evangelion; many fans suspect this was done so that his mouth movements didn't need to be animated.
R4, C14: A play on "Bond, James Bond".
R5, C3: The main female lead from "The Melancholy of Haruhi Suzumiya"
R4, C15: A parody of the iPod commercials.
R5, C4: "Needs more jiggawatt's" is one of Emmitt Brown's recurring phrases from the "Back to the Future" series.
R5, C5: The Prince of All Cosmos, the main character from Katamari Damacy.
R5, C8:
Kill It With Fire (I'm guessing this is some sort of B-horror flick?)
R5, C12: A Koffing is a pokemon that emits smoke as one of its attacks.
R5, C14: "Hey! Listen!" was what that annoying little fairy in Ocarina of Time would never stop saying if you were on some kind of quest.
R5, C15: "Jesus Christ, it's a lion! Get in the car!" was apparently from some commercial that became a /4chan meme.
R6, C11: A reference to the Dutch cartoon depicting Mohammed's turban as a bomb.
R7, C2: "Oraoraora(etc.)" was the battle cry from Fist of the North Star.
R7, C5: Mudkip was one of the three starting pokemon you could use in Pokemon Diamond/Pearl, but due to various reasons was considered the least popular. At some point on one of the Pokemon message boards someone confessed to liking the Mudkip, and it became a /4chan meme from there.
R7, C14: "Kage Bushin" is a technique name from the anime Naruto in which the user can create a large number of shadow clones.
R8, C2: A character from the anime Digi Charat (I forget which off the top of my head).
R8, C8: The "ORLY?" owl is a picture of an owl that looks surprised and/or incredulous. ("ORLY?" is internet speak for "Oh, really?")
R8, C8: The Pedobear, another /4chan meme.
R8, C15: "There are four lights" is a reference to a Star Trek: The Next Generation episode that I'm too lazy to look up the name of.
R9, C2: "R" is a reference to International Speak Like a Pirate Day.
R9, C3: A reference to how Tom Cruise claimed that he was going to eat his wife's afterbirth.
R9, C5: A parody of the typical wild Pokemon battle encounter.
R9, C7: "Longdue is long" is a parody of "Longcat is long". I don't get it, either.
R9, C12: Rei Ayanami from Neon Genesis Evangelion.
R11, C8: Spoiler for Cowboy Bebop.
R11, C9: A reference to the comic/horror film "Uzumaki" (Spiral)
R11, C10: Goku from Dragon Ball Z as a Super Saiyan.
R11, C15: A quote from the first "Legend of Zelda" game.
R12, C13: A "trap" is internet lingo for a crossdresser (usually a male masquerading as a female; female crossdressers are referred to as "reverse traps"); also a reference to Admiral Akbar's famous quote in "Return of the Jedi".
R13, C2: A scene of James, Mewoth, and Jesse from Pokemon.
R13, C5: Aeris from Final Fantasy 7.
R13, C13: Luffy from One Piece.
R14, C2: Pyramid Head from the Silent Hill series.
R14, C5: A quote from the Dune series.
R15, C3/C4: Reference to the "Phoenix Wright" series.
R15, C9: Yotsuba from the comic of the same name.