iFile is an advanced file manager for jailbroken iOS devices.
Running under the user root, it allows for fast navigation of the iPhone file system. You can directly access and view any file of any type on your device.
Files can be sent as email attachments. Certain files (i.e. deb files) can be installed on your device using the built-in installer. Text files and property lists can be edited. Folders and files can be bookmarked. In addition, files can be uploaded and downloaded from a built-in web server. More Info »
You can get iFile from the Cydia app store (on jailbroken iOS devices). The trial version can be used indefinitely-- however, after the trial period expires, iFile will display a popup once per day asking you to buy the app. The full version of iFile adds several extra features, including file name search, external viewer support, displaying of song titles instead of file names for audio files, displaying of thumbnails instead of default icons for images, and text editor search functionality.