Once I download Filezilla from its website, The Unarchiver decompresses it in a weird manner, which creates "FileZilla_3.3.1_i686-apple-darwin9.app" instead of "FileZilla.app."
The strange file is even not executable, only showing an error message.
While Mac OS X Archive Utility does the job correctly, The Unarchiver keeps the same problem even after some bug fixes and version 2.2 still fumbles.
Please check this out. You can download the Filezilla file in BZ2 format at following link.

https://www.ohloh.net/projects/filezilla/download?filename=FileZilla_3.3.1_i686-apple-darwin9.app.tar.bz2

http://pqrs.org/macosx/keyremap4macbook/files/KeyRemap4MacBook-5.1.0.pkg.tar.gz did not unarchive properly for me with latest version (2.2). It appeared to work but the resulting file gave an error when opened.

Built-in Leopard archive utility was successful. I'm on 10.5.8

Thanks.