I do love a good International Scientific Year, and I was born in this one, so it seems a bit special.
The IGY was aimed at taking advantage of a solar maximum; the IQSY (International Quiet Sun Year) was all about the solar minimum. There were some satellite missions launched specifically for it, but I'll need to do a bit more research to find out which ones.
An interesting article about planning the IQSY can be found here:
Martin A. Pomerantz 1963 International Years of the Quiet Sun, 1964-65 Science 142(3596):1136-1143
The International Quiet Sun Year is a lovely notion as it implies that the Sun is usually noisy - like it was singing to us. (I'm sure someone must have translated solar activity into music before).