Three days in Tokyo

A friend and myself are planning to spend three days in Tokyo (April 22nd to April 24th).

We have each purchased travel guides about the city, and Japan in general, but there is far too much to do in three days.

What suggestions would people make for 'must-sees' in Tokyo?

Many thanks,
Summerfayre

What to see is a personal choice: I like both fancy department stores and old fashioned residential areas, temples etc. others wouldn't be interested at all.
first define your likes and dislikes, it might help others to steer you in the right direction

I just went on a holiday to japan and spent 4.5 days in tokyo (2 of those being day trips to nikko and Kamakura). We stayed in west shinjuku and did something like this.
Day 1: Shijuku - train to Shibuya, then walk Harajuku.
Day 2: Subway to Tsujiki fish market, Akihabara electric town, then to Ginza (or maybe around the imperial palace).
Day 3: Day trip to Kamakura to see temples and shrines.

If you use the Yamanote line (which circles the inner city above ground) see:
http://www.japan-guide.com/e/e2370.html
you will not only get an inexpensive tour of Tokyo but will go through major train stations that have "downtowns" around them. For example, the East Garden of the Imperial Palace, Hibiya Park, the Yurakucho and Ginza shopping areas, Tsukiji fish market and Hamarikyu Garden are within walking distance of Tokyo or Yurakucho stations. Shinjuku, Shibuya, Akihabara, Ueno (and nearby Asakasa) and Ikebukuro all have giant department stores, temples, parks etc around them. Akihabara is the electronics center of Tokyo and is especially colorful at night. When I say "walking distance" I'm 58 and in fairly good health so several kilometers of walking is easy for me. Hope you have a fun time.

It depends on what you want to experience, because there are too many stuff in Tokyo. If you are seeking something most travelers do, then just visit Tsukiji fish market, shibuya and harajuku. You can also get useful info on http://www.sunnypages.jp

I suggest the sights with the two red dots:
http://www.japan-guide.com/e/e2164.html