This is a Step-By-Step-Tutorial-For-Morons how to do a tiling wall texture. wooohoo. For this you will need Photoshop (preferably 4.0 or later) and know how to use rubber stamp tool. Read the help file in case you aren't familiar with this tool.

1. Make a new image, 200x200 and a grey background about this color :

2. Use the 'Texurizer' plugin located in Filter-->Texture

with the settings:

3. Now, go to Quickmask mode (key Q) and airbrush this kind of selection:

Now go back to normal mode (key Q again) and add the texturizer filter to the selection with the same settings as before and then, using the pencil tool, color the selection with 30% opacity black and you should have this kind of image now: (btw, saving the selection wouldn't hurt in case you want to experiment a bit)

4. Now do a 'Select All' and then go to Edit-->Define Pattern:

then go to Image-->Canvas Size

And resize the canvas' to 200% :

then, go to Edit-->Fill

Fill with pattern:

Now you should have something like this (the pic is resized) :

Now, working with a 200x200 selection, flip the top and bottom right corners horizontally :

Now comes the fun part where we totally rape the picture with 'Rubber Stamp Tool'(key S) and 'Airbrush' (key A in PS4.0 and key J in PS5.0) ;)

so what i did here, is with airbrush and rubberstamp i got rid of the seams and borders. the red areas are the areas you should pay special attention to, as these areas are the ones you must make seamless. the key here is to experiment and make it to look as non-patternic as possible. and yes i know this is a bit ...strange, not suitable for a web page, for example, but this could be used as a base texture for a new texture, as a bumpmap, wrapped arounda 3d stone, etc etc the possibilities are many.

Heres a simple wall with the texture applied , 2x2 tiled:

Yadda dadda. Thats about it.