Not that i've ever done anything like this...

Well. A shatter effect could be done by, when the shatter effect is "playing", render the scene to a texture and map that texture onto some polygons which have made to look like shards (just simple surfaces should do it, no volume) and move them around acording to some basic physics.

Geez sounds heaps complicated. If you want an idea of what I'm looking for, check out

http://www.pompomgames.com/spacetripper.htm#stdownloaddemo

http://www.garagegames.com/pg/product/view.php?id=18

Not only is it a cool game, it has some nice graphics.

Any ideas how to do those trippy backgrounds too?

I don't know OpenGL or any 3D graphics library at all. But couldn't you just have a black quad right in front of the "camera" within the game. It begins as 100% translucent and gradually shifts to 0% translucency (i.e. everything goes black). Then you do the opposite to fade back..... Or?

I usually do fades transitions by putting a screenshot to a texture, and then playing with it in any way I please.

For example, a fade to black effect can be done with a single quad (textured with the screenshot) and glColor3f. A fade to white can be achieved by using the same quad accompanied by OpenGL fog. Multiple fun effects can be done by scaling/rotating the quad and blending it with the previous contents of the screen (this can result in a radial blur, a swirl blur, the screen floating away along the Z axis, or something I call "light blur" achieved with additive blending, and changing the screen dimensions).

Shattering the screen with that method would be as easy as randomly dividing the screen quad into polygon shaped shards.

This technique has only one drawback - the screenshot texture doesn't change during the transition, which can look awkward for long-lasting effects (say, over a second). If your effect is short enough, nobody will notice a thing.

Of course, that problem can be remedied by rendering to the screenshot texture each frame, and then rendering the transformed quad textured with it, but that can be troublesome.

Just call me Jakub, and I have no problems sharing my sources - but in my projects the code responsible for screen grabbing and transitions is custom tailored to my engine and interspersed in several places (separate logic + rendering), and probably wouldn't be of much use.

There are multiple ways to render to texture, but if you already have everything on the screen (i.e. you want a screenshot texture), you can use this:

  glBindTexture(GL_TEXTURE_2D, textureID);
  glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, SCREEN_W, SCREEN_H);

TextureID must be a GLuint pointing to a texture that can hold at least SCREEN_W x SCREEN_H pixels, and is in some format that can hold the framebuffer contents (which usually means that you want GL_RGB).

[EDIT:] Forgot to mention - you don't have to have the picture on screen - it can safely be grabbed from the backbuffer, and you can clear the backbuffer afterwards. But that's just a sidenote [/EDIT]

As for each polygon getting part of the texture - OpenGL allows you to use any fractional number as the UV (texture) coordinates of a vertex. Please look at the attached picture, where I tried to demonstrate splitting a screen quad into 4 "shards", and added UV coords to each vertex.

The coordinate system has the V axis increasing downwards, that is different in OpenGL, but the idea is the same - you take each of those shards, store X and Y positions of each vertex, then store U and V texture coords along with them. Then you just use an appropriate combination of glVertex* and glTexCoord* to render your shards, along with some rotates, translates and scales if you want to have a basic shattering glass effect.