Data sets for download

Hello all,
Does anyone know of reasonably-sized data dumps (csv or excel or xml..) that can be used for learning/teaching about performance tuning. Say - a set of 6-7 tables, may be two of them with a few million records etc? Total data volume would be in a few GB range. There are tools which generate data, but most of them seem to generate junk data. I came across this one (pretty good) -
http://www.ourairports.com/data/
If there were schedule and bookings tables to go with this, it would have been great.
There is http://www.imdb.com/interfaces also. But the data extraction process not simple.
Anything similar - the typical warehouse/customer/order tables or emp/dept/project ?
Regards,
Jayadevan

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