There are many many pdf to epub readers out there, it's just a matter of finding one that suits your personal needs, however, as you know the ipad can read pdf's via ibooks or if your jailbroken, there are many other alternatives such as ifile or even the builtin pdf viewer which is part of mobile safari.
Hope this helps, most converter tools are pc based so the conversion will be to be done offline then the epub pushed to the ipad via itunes.