These make sense when you try them, and can see what I'm talking about.
Extra Long (I): take two rolling papers, lick some of the glue of one of them. Stick the two papers together, so that they overlap with the edges in parallel. What you should have should look like an extra long rolling paper, so proceed to roll like you normally would. Be sure to have the papers connected so that the glue is on the same side, so that it is one long line.
Extra Long (II): Connect two papers, but in an "L" shape. Stick paper1's wet glue onto the very edge of paper2. Before starting to distribute the chosen substance, fold paper2 like normal, along the crease, but continue the crease along onto paper1. When you roll up, roll it as you would normally but you will need to wrap the extension more times than the other part of the blunt, as the whole of paper1 is waiting to be used. This isn't as long as Extra Long (I).
Extra wide: Take two papers, and lick the whole of paper1's glue. stick this along the edge of paper2, the edge without the glue on it, otherwise you'll end up with an extra wide paper with glue in the middle but no glue on the edges. Some people prefer to stick the two papers together at an angle, so it has more of a cone shape, and a thinner end to insert in the mouth. This will cause an extra flap of paper in the middle, which can either be left to burn or ripped of, gently, once the glue has dried.
The Flatty: take two papers and stick them together, like the extra thick. Then, in the end you wish to put in your mouth, put multiple filters or roaches (3 is a good number). Keep then in a line as you roll, so that when you finish you have a nice wide mouthpiece. Gently flatten the joint on a table or cd case (whichever is nearest) so that the joint takes the shape of the filter-end. This will give you quite a headrush.
The Mustache: make yourself an extra long roach, then roll a joint on each end of it. But how would one smoke it? No worries. Poke a hole in the middle of the roach. When the two ends start getting nearer to each other, and you start feeling the corners of your mouth getting burned, you should be able to slide one joint off the roach (if you haven't rolled too tight) and have two seperate joints. This is a pointless structure, but it's a good party trick for family reunions.
The Triangular: Stick two papers together, then take three filters or roaches. (If you use roaches, try and make them the same size.) Place two of the filters/roaches next to each other in the filter-end, and one on top, so you have a triangular shape. (^) Roll with this, and try to keep it together in the pyramid shape. Once the rolling is complete, flatten each side on a table (or be cool and use that cd case) to sharpen the edges and corners. Ta-da. Very cool, but very pointless. It has recently occured to me that one could, if they were feeling idle enough, take 6 roaches, or even 10, and make some properly huge 4-3-2-1 triangle of a mouthpiece, and have some big-ass triangular joint. Hm....
The square: Much the same as the triangular, but use 4 roaches to have a square-shaped end. This will fit better in your mouth than a triangle. I figure if you use a big enough paper constuction, and enough filters, you can pretty much make any geometrical shape. Heh.