A list of Features from Fedora 11 LXDE's wiki :
* PCManFM: File manager, provides desktop icons
* LXPanel: Feature-rich desktop panel
* LXSession Lite: Standard-compliant X11 session manager with shutdown/reboot/suspend support via HAL and gdm
* LXAppearance: LXAppearance is a new feature-rich GTK+ theme switcher able to change GTK+ themes, icon themes, and fonts used by applications
* LXTask: Lightweight task manager derived from xfce4 task manager with all xfce4 dependencies removed, some bugs fixed, and some improvements of the UI
* LXTerminal: Desktop-independent VTE-based terminal emulator
* LXLauncher: Open source replacement for the Asus Launcher on the EeePC
* LXNM (still under development): Lightweight network manager for LXDE supporting wireless connections
* LXRandR (still under development): Monitor configuring tool.
* Openbox: Lightweight, standard-compliant, and highly-configurable window manager. This can be replaced by any other window manager like icewm, fluxbox, metacity, ...etc.
* GPicView: A very simple, fast, and lightweight image viewer featuring immediate startup
* Leafpad: Lightweight and simple text editor
* XArchiver: Lightweight, fast, and desktop-independent gtk+-based file archiver
Official Site : http://www.lxde.org/
after reading about XFCE vs LXDE discussions, it seems that LXDE can save from 15-50MBs in your RAM usage. Can run any Gtk and QT application but you must have Gnome and/or KDE installed. You should have no problem finding it in your Distribution's repository and if all else fails you could install from source. I also found that LXDE has a lot, for less than a 10 MB install in most distributions (my Fedora 11 install was less 3 MBs)
I have to give them a plus for using OpenBox and Leafpad. Leafpad is the most lightweight Graphical Text Manager I can think of. OpenBox is a nice addition but lacks some easy configuration tools that XFCE has. PCManFC is an excellent File Manager and takes a little to get used to but as many features of Thunar. I would seriously give LXDE a whirl. I'm currently going to try to go 7 days with it. Myself, I'm usually a XFCE boy and used GNOME occasionally. I tend to flip flop between Windows Managers.