If you open the DSK image in Disk Manager (the program people around here generally suggest using for writing DSK files to disk), you can drag and drop any of the contents of the DSK into other folders on your computer. So even though Disk Manager is meant as a disk writer, you can also use it kind of like a DSK unzipper if you want to.
it can't handle subdirs (yet)... you've to copy the files to the root using an emulator to get them out of the dsk using disk manager. other than that, great tool.
I would recommend DiskExplorer. There still a bug affecting DiskMgr when copying big files. It rarely occurs, but at some point, the FAT or Directory gets corrupted.