There are several:
if your into modernism, check the Weissenhoffsiedlung is a must-see. It is about a 10 minute bus/u-Bahn ride from the main train station (itself by fascist celebrity Paul Bonatz). Downtown, there is James Sterling's museum: green rubber floors, post-modernism at its best. Sprinkled around the suburbs are several Behnish buildings - if you have a car, get out to them, but otherwise, they can be tough to get to.

the Weissenhoff Siedlung exhibition was in Stuttgart and can still be visited: Mies, Corb, Taut... the gang's all here!

Stirling's Staatsgallerie is a must. If postmodernism makes you want to puke or if you were before in some of the late Stirling barbarities in London, even better, because you will be surprised at how good this building is.
(note I am only referring to the gallery not to the other buildings around it)

Go to the tower in the trainstation, nice view and they usually have an exhibition there. http://www.0lll.com/architecture-exhibitions/?gal=17&pic=1 this is what I saw.

Take the tram (dont remember the number sorry) to Ostfilden, a suburb where you will see Jurgen Mayer's townhall http://www.0lll.com/lud/pages/architecture/archgallery/mayer_stadthaus/index.htm
This suburb is still under construction, building codes seem to be pretty strong, you can walk around there and see a bit of German contemporary urban planning.

Ditto on the Sterling Museum and the Porsche Factory & Museum is a short metro ride out from downtown Stuttgart.

Also, Ulm is a semi-short train ride (between Munich & Stuttgart) to check out the gothic cathedral and Richard Meier museum right in front of it.

1
go to the top of the Fernsehturm Stuttgart [the world's first tv tower built out of reinforced concrete--protoype for many towers of its kind]

2
Main Station, Stuttgart [being built]
Architect: Inghoven und Partner [check out their site for pics]
link

I think there is a permanent exhibition of this in the mercedes tower adjacent to the mainstation...worth checking out

3
stuttgart=home of frei otto
check into visiting the
Institute of Lightweight Structures

4
Porsche/Mercedes museums

Since when is the Ingenhoven station under construction? I didn't know whether it already started.

thanks guys for ur help.... it was a cool quick tour...yeah have to come back to check all of stuttgart amenities...u guys forgot something and im about to post them in the gallery is the new mercedes benz museum building by BEN vanBerkel (UN Studio), theres also a (suppose to be) new kunstmusseum (museum of art) in the center od stuttgart by a local guy, and its a pretty good looking builidng also.... anyways thanks... now its monday and back to work...

did you get around to posting those pics of the museum, mad?

sorry not yet... fixing them to 400 width and 72 dpi for screen viewers...but tons of 'em

give me 45 more mins...

AWESOME!

nice photos - thanks for sharing.
what was your impression of the building? It looks
really interesting in photo and was guessing that it's
much more revealing, spatially, in person.

well still i miss to upload like other load as the first one, but the server got tired of me, and wont let me upload more
i would try tomorrow or later
there's better pics
yet