Browser FTP app

We’ve always used standard browser FTP to enable clients to upload/download large files to/from us. Our host has implemented changes which negate the use of this process. I’ve seen other sites that have a client login site that allows drag and drop ability to upload or download files dirctly into or out of the browser window. The windows look “Explorer-like” with large icons representing individual files or folders. I’ve searched HotScripts and other script sites for a solution but can’t seem to find one. I would prefer a non-ASP solution because my host is a Unix house, but I’m not beyond buying another domain and hosting on a Windows server somewhere to gain this functionality. Is anyone familiar with a solution for this?