Web Elements
Web Elements Periodic Table: Helium
A very nice site with all sorts of information on helium, including good summaries on isolation and uses of helium.
University of Colorado
University of Colorado: Ph Et Interactive Simulations: Balloons & Buoyancy
Experiment with a helium balloon, a hot air balloon, or a rigid sphere filled with different gases. Discover what makes some balloons float and others sink.
Other
Virtual Chembook: Density Applications With Gases
DENSITY is a physical property of matter, as each element and compound has a unique density associated with it. Density defined in a qualitative manner as the measure of the relative "heaviness" of objects with a constant volume. For...
CK-12 Foundation
Ck 12: Chemistry: Noble Gases
[Free Registration/Login may be required to access all resource tools.] Covers electronic configuration of noble gases and the reactivity of noble gases.
Other
The Elements: Noble Gases
A listing of the noble gasses can be found here as well as images and links to additional information. This site is maintained by a high school chemistry teacher but is supplemented with information from the Los Alamos National...
Ducksters
Ducksters: Astronomy for Kids: Stars
Kid's learn about the science of stars like our Sun. Giant hot balls of gas and energy made mostly of hydrogen and helium.