Sure, it's not a replacement for Windows Mobile's File Explorer, but it is something. davux from XDA Developers has released a homebrew webserver for Windows Phone 7 that lets you browse and download contents from your phone's Isolated Storage and Windows directories. The application doesn't have access to the root of the device, unfortunately, but it will enable you to download EXEs and XAPs inside your device's Windows folder, which is certainly something to feed curiosity.

Another significant part of this project is the development of a Sockets and System.IO library, which in layman's terms will enable real-time Socket applications and better support for managing files on your device. The code is still in early stages, but the project looks promising. You can check it out here. 

[Source: XDA Developers; Via: MobilityDigest]