Sources for data sets:

Altitude data (altitude.txt): NOAA 2-minute Gridded Global Relief data set.
For details see C. Amante and B. W. Eakins, ETOPO1 1 Arc-Minute Global
Relief Model: Procedures, Data Sources and Analysis. NOAA Technical
Memorandum NESDIS NGDC-24, March 2009, or visit
http://www.ngdc.noaa.gov/mgg/global/global.html

Star magnitude/temperature (stars.txt): HYG Database, a composite of data
from Hipparcos and the Yale Bright Star and Gliese catalogs, compiled by
David Nash.  See http://www.astronexus.com/node/34

Sunspot numbers (sunspots.txt): NOAA National Geophysical Data Center,
based on a data set maintained and published by Royal Observatory of
Belgium's Solar Influences Data Analysis Center.  See
http://www.ngdc.noaa.gov/stp/solar/ssndata.html

Recordings of piano and trumpet notes (piano.txt and trumpet.txt):
University of Iowa Electronic Music Studios.  See
http://theremin.music.uiowa.edu/MIS.html