Because I'm making an online game that will allow character customization. So if I added all clothes and parts in one single file, it would grow in size a lot. And we all know that would make parsing eternal.

I'll just stick to handling them separately... I already got that done, I was just looking if there was a more efficient way.

Do I just handle them separately, or is there a way that would be more optimized?

It's a mix of removeAndUnload and my attempt at cleaning the resources raft's GLFont uses. With what you've told me, I should be able to fix it now (since I already did some changes to texturePack for disposal) -or since it's a font, I might as well leave it-
All the rest remove and unload their textures correctly without triggering that error.

EdIT:

Keep in mind that if you remove a texture and add the same texture with the same name, an old object using this texture will still refer to the old one. Maybe that causes the problem?

And yes, this was the case... I hadn't seen GLFont kept a cache.

As far as I know, I'm not using concurrency (at least not explicitly), so I guess I'm in the render thread. And damn, didn't know I was leaving those textures like that.... thanks.
And for this project, leaving the textures I don't think is an option, because I want the game to run in any video card from Pentium 4 integrated and up, and I'm making a Pokemon-like MMO... which means there will be around 100 different creatures with different textures in different fights, so if the client were to be left open for extended gameplay, those and the player (which will be customizable, increasing the amount of textures) and terrain textures will build up.

removeAndUnload can only cause that if you are still rendering objects that use these textures.

What do I have to do then? Inside my loop I have:

display();
changeRoom();
removeTextures();
Thread.yield();

private void changeRoom(){
 if(nextRoom!=null){
room.dispose();
world.removeAll();
sky.removeAll();
switch (nextRoom) {
case TITLE:
room=new Title(this);
break;
case GAME:
room=new Game(this);
break;
default:
break;
}
nextRoom=null;
}

private void removeTextures(){
for (String name : texturesForRemoval) {
TextureManager.getInstance().removeTexture(name); //This is the line that will become removeAndUnload()
}
texturesForRemoval.clear();
}

So, I thought since the objects are removed before the textures unloaded they should have already be "Not rendered".

Yes, as you can see, the weights for that bone are not Red, but yellow. That's like a 0.5 weight. Blue is 0, vertices not affected by that bone will be blue. And Red is 1, the max weight, where they will be completely affected by the bone.

Also, there's nothing wrong with vertices being part of 2 groups... the problem is if they are part of groups that are too apart: The vertices of the knee can be part of both the thigh and leg. But, I'd recommend to keep them to a minimum... in the preview image it looked as though some vertices were part of both the hand and head for example.

And, I'd recommend NOT to use blender's automatic weights as they won't be 1.0 (Red) and may even be badly done. Doing them yourself gives you more control and makes them right. And with weight paint, it doesn't take too long.

And last, I don't like video tutorials P: but here's the one I had used to learn about weight paint:
http://wiki.blender.org/index.php/Doc:2.4/Tutorials/Animation/BSoD/Character_Animation
It's pretty complete. Go to the middle, to the Rigging section

add a picture of your original model too.

Alright, thanks!
I changed my code accordingly using just world.removeAll(). Also, found out that the error was being caused by textureManager.removeandUnload(), so I'll just use remove() when there are textures I'll have to remove (because yes, there will be some rooms that have objects with very unique textures, and several of those)

So, on my original attempt to do so, I got
[ Thu Jan 05 03:46:05 CST 2012 ] - WARNING: There's a problem with the object list not being consistent during rendering. This is often caused by concurrent modification of jPCT objects on a thread different from the rendering thread!
[ Thu Jan 05 03:46:05 CST 2012 ] - ERROR: nullBut, only with the OpenGL renderer and if it's the second time I go into the Game room. (the only other room is a title screen that only blits 2d stuff with raft's openglFont and texturePack)

I guess it's related to the way cleaning must be done in between rooms. Is there any example on it?

So far what I do is call world.dispose(); and textureManager.removeandUnload() for every texture I can keep track of after rendering and before creating a new Room object over the previous.