There is far too much to Tokyo to write in one entry here. I will attempt to put the most important (for a tourist's point of view) things here today. I will add more as I think of things.
MONEY:The most important thing I can think to write is to remember to bring cash. It is easier in Tokyo than in the rest of Japan to find places that accept credit card, but it can still be frustrating at times. You can always get cash from post-office ATMs (Look for a symbol that resembles a large red 'T' with an additional horizontal line at the top) or at a Citibank (Shibuya has one that is easy to find. Right past McDonalds).
Tokyo runs on trains. When you get to Tokyo, get a SUICA card (similar to Boston's Charie card) for use on the JR lines. You will frequently have to switch between JR and the Tokyo Metro lines, but a SUICA card will at least allow you to bypass ticket lines when riding the JR trains. If you do not wish to spend all of your money in one go, avoid taxis. They are a sure way to run out of cash fast in Tokyo. If you plan to stay more than a few months, buy a bike. Most bikes are decently cheap (under 100 dollars) and come with baskets to hold your things and a dynamo-powered headlamp for riding at night.
If you are looking for good sushi, go to Harajuku station (原宿駅) on the Yamanote line (山手線) (The big green circular line). When you exit the station, everyone will head for an alleyway to the left of a giant Snoopy shop (not Peanuts, just Snoopy). Go to the right of this shop and take the elevator to the 3rd (I believe, though it may only have been 2nd) floor. There are two restaurants here. Go to the sushi restaurant on the left called Kakiya-Zushi (柿家鮨). You will most likely have to wait a half hour or more to get a seat if you aren't alone, but it is definitely worth the wait. While this is a kaiten (conveyor belt) restaurant, their sushi is among the best I tasted while living in Tokyo.
Never be afraid to try something from a street vendor. Street vendors sell some amazing food. Not to mention, they usually set up in the same place each day making them fairly reliable as landmarks.
When you want dessert, try a milk tea or crepe from Pearl Lady (In Shibuya. Look for Book 1ST. Stay on the left side of the street (across from the book store) and continue away from Shibuya station. You will round a corner and pass a soap shop. Pearl Lady is a recessed shop on your left.). Else you can look for a parfait restaurant. These are easy enough to spot from their flamboyant displays. No one can ignore that many parfaits lined up and lit in a window. It's simply not possible.
Head to Yodobashi-Akiba in Akihabara. Take the green Yamanote line (山手線) to Akihabara Station (秋葉原駅). Electric town is on one side of you (always worth a visit) and Yodobashi Akiba is on the other through the Showa Dorii exit. You will take a left before you reach the street, pass a bakery, and the entrance is on your right.
If you want to embarrass yourself or others, or if you really need those handcuffs and that costume, go to Akihabara station via the green Yamanote line (山手線). Exit through the Electric Town exit. You will be facing a large electronics store that remotely resembles your 10th birthday party due to the large glass tubes that house the escalators. Turn right and follow the street. You will see a neon pink awning when the street Ts out at the end of the block (Electric town continues to your right for some blocks and is worth a visit when you get your curiosity back under control). That's your happy place. Else, you can walk toward the electronics store and pass it to the left. Take your first right and encounter a second store on your right (Yes, there are two in one block). This one has a more plain front and is harder to distinguish. It is the last door on the block. There are far more than these if you are willing to search. By all means, enjoy yourselves.
Since some of you may be students at Sophia University in search of Western food, I will list a few restaurants that are NOT McDonalds. First, you can get a good selection of Western beers at Za Morrigans (Turn right out of the main gate to Sophia's Yotsuya campus or take the yellow Chuo line to Yotsuya station, exit, and head toward the campus. The bar is about 2 blocks past the post office.).
You can also find a Subway if you go the opposite direction across the bridge next to Yotsuya Station. At the end of the bridge take a right. The Subway is on your left.
If you really want to party, head to Gas Panic. There are several of these spread all over Tokyo, but the best is still the "red" Gas Panic in Roppongi (anyone can identify it if you describe it as this). This bar is two floors of liquid insanity. From the female patrons dancing on the bar to the bucket of viagra on the second floor, nothing is ever boring here (unless you come on a Tuesday night. stick to the weekends and you'll be fine.).
If you want a more relaxed and personal atmosphere, but still want to get away from your part of town, head to Azool. Also located in Roppongi, Azool creates an amazing atmosphere by using private, themed rooms for parties and curtained tables for couples. To reach Azool, simply head toward Roppongi Heights from Roppongi station. Pass Roppongi Heights and continue straight for about 1 km. The entrance is on your left. The exterior is fairly subdued, so keep your eyes peeled and look for a wall of running water.