Everyone should already have the Exploritorium. It has a lot that is useful.

The international space flight museum is cool.
http://maps.secondlife.com/secondlife/Spaceport%20Alpha/30/61/22
paste the link in at the top of the secondlife viewer. Then just go stand next to a tall rocket and fly to the top. Its great for showing how big the things really are. Then show the kids how designs all follow the same pattern. They are all aerodynamic, narrower at top, and with huge engines, no matter what country built the rocket.
external image space%20and%20aeronautics%20museum.jpgspace_and_aeronautics_museum.jpg

NASA jet propulsion lab
http://maps.secondlife.com/secondlife/Explorer%20Island/91/253/26
As you can imagine it is NASA and has a lot of cool things to explore. RIDE THE ASTEROID!
NASA_JPL.jpg

Institute of physics
http://maps.secondlife.com/secondlife/Rakshasa/212/20/26
This site has terminals that you can use to open links to web sites with physics java apps and other lessons.
physics_applets_site.jpg

Elucian island - Nature publishing
http://maps.secondlife.com/secondlife/Elucian%20Islands/141/158/22
http://maps.secondlife.com/secondlife/Elucian%20Islands/48/193/32
they have a giant cell you can enter to see all the organelles floating around. They have DNA and other displays also. It is at the science park area. The teleports seem to all face you backwards from where you want to go on the island.elucian_island.jpg
elucian_island2.jpg

Second Elon
http://maps.secondlife.com/secondlife/Elon/211/193/39
This site has some good models of biology and space science. It also has displays of environmental science stuff.
This island, funded largely by grants from Elon University, is dedicated to providing a space for STEM (Science/Technology/Engineering/Mathematics) undergraduate students to work in mentoring scenarios with teachers.

Sbarro Health Research Organization
http://maps.secondlife.com/secondlife/Biomedicine%20Research%20Labs/81/131/22
Has the same displays of 3D objects as the site above but it's hard to get around and find things because the teleports would not work for me.

biomedical_research_labs.jpg

Astronomy
http://maps.secondlife.com/secondlife/Astronomy%202009/2/130/28
I haven't explored this one yet. The picture is an astronomy site. The island I am facing away from in the picture is a computational astronomy site.Astronomy.jpg

NMC resource center
http://maps.secondlife.com/secondlife/Learning/94/142/25

This site ha a few models that are nice to look at for biology chemistry and physics.Blood_cell_and_skin_001.png