So here's a list of what I think LXDE is lacking.
As LXDE is not aimed to be a full all-in-one suite, I think we need to 
focus on finishing the most vital core parts of a DE.

1. Power manager, a very basic and important system service.
We can use upower for this. It's not a bad idea to get some code from the XFCE one.
The Gnome one is deeply integrated with gnome-settings-daemon and it's hard to extract useful parts from it.

2. A X11 composite manager.
To have a more modern look, I'd suggest that we include a composite manager in LXDE.
I tried several ones and found "Compton" a nice and very lightweight choice.
Maybe we can create a Compton plugin for lxappearance so it can be turned on/off in lxappearance. The only problem is, it's not yet in some major distros.

3. The desktop panel needs some rework.
Since Andriy is now working with the file manager, I think I can have some time for the panel later. Give me some more time. If I fail, let's find an good alternative from other projects.

4. A application menu editor.
I don't think creating an xdg-compliant menu editor is right. The xdg menu is bad for editing. Although it has menu editing support, it's very basic and cumbersome.
That's why it's so difficult to create a nice menu editor.
An reasonable alternative, IMO, is to have our own menu definition file, just like all of the old window managers does. Of course, this should come with a GUI editor not requiring the user to write that menu file with a text editor.
Moreover, the user should be able to choose the apps he likes from existing applications (defined in xdg application menu) and add them to the menu.
This is simple and should always works.
Xdg menu only serves as a repository of all installed applications. The items in the menu presented to the user can be different from that.

5. A good place to gather all configuration tools, something like a control center. This should be quite easy to do. Existing code for Lubuntu can be reused.

6. Last but not the least. A potential way which might further improve the situation is to elect a new project leader/administrator who is less busy and is more reachable via either forum or mailing list. This is very important. I can still be a developer devoting to writing source code and maintaining some components. This should give the project more vitality.
Any ideas?

LXDE is still a relatively young project and has a long way to go, but I believe that we'll find our way.