Anyone using a free and good pdf compressor?

[Sakura]

I have 8860 pdf files made with OpenOffice but for some reason they're incrediby large. Anyone knows of good free tool to make them smaller? Acrobat Professional can do that but it's 700 Euro (currently US$1300)

[Dechant]

PDF Compression

It says some are free, but are they also working and useful? Who knows~

[Sakura]

Thanks doesn't work