my incomplete list of technical places:

Peter Apian-Bennewitz
Where's what:
What Where last visited highlight
Tokomaru Steam Engine Museum Tokomaru, NZ, approx. 50km south of Palmerston North) , see www.tokomarusteam.com March 2001 Impressive private collection of steam engines in operating condition. Enquire about times where they run them on oil fired boilers. Phone: 063-298-867
Collins Brothers Sawmillers Ltd Kerikeri, NZ, Inlet Road, phone +64-9-407-9707, colbros@xtra.co.nz March 2001 commercial sawmill powered by steam, energy-wise self sustained, excellent tours
Powerhouse Museum Sydney, Oz Jan 97 Steam driven engines, including merry-go-round featuring compressor driven organ (deafening), 'smell test' to show how smelling works (the only one I've seen so far),
MOTAT (Museum of Transport and Technology) Auckland, NZ March 2001 Early tramway running on 3km track, steam operated engines, aeroplane hangar exhibition (e.g. refurbished flying boat), early settler cottage, agriculture machinery
Umekoji Steam Locomotive Museum Kyoto, Japan 15.9.99 18 Japanese steam locomotives, 6 in running condition, round house, turn table, oldest wooden railway station in Japan (1904),
Computer Museum Boston, USA Sep 89 history of computers, with the old mega boxes still alive. Update: They shut down and merged to CHM (see below)
Computer History Museum Mountain View, CA, USA Nov 2008 history of computers, *lots* of hardware, see www.computerhistory.org
Exploratorium San Francisco, USA May 95 Disney Land meets the sciences, nicely done
Science Museum London, UK Sep 90 history of steam engines, many others
Deutsches Museum München, BRD 91 Pioneering (IMHO) push-and-look demonstrations of all technical aspects of the last centuries. Two weeks are about the minimum time for a good look. Goody: Demonstrations of basic physical law for pupils and phd's alike.