IPod Classic 3rd party manager

Question

Is there a 3rd party music manager that works with ipod Classic? If not yet, when can we expect to have one available?
It appears that with iTunes I cannot keep music on my iPod unless I have a copy on my computer hard drive. If I delete the song from my hard drive it will be automatically deleted from my iPod? I do not want to keep any music on my hard drive, but want to keep it all on my iPod. How can I solve this problem?
Thanks and good luck.