Another alternative is to generate noise using libnoise libraries. You can generate noise over a theoretical infinite amount of space, seamlessly.

Take a look at the following: http://libnoise.sourceforge.net/tutorials/tutorial3.html#tile

There is also an XNA port of the above at: http://bigblackblock.com/tools/libnoisexna

If you end up using the XNA port, you can do something like this:

Perlin perlin = new Perlin();
perlin.Frequency = 0.5f;                //height
perlin.Lacunarity = 2f;                 //frequency increase between octaves
perlin.OctaveCount = 5;                 //Number of passes
perlin.Persistence = 0.45f;             //
perlin.Quality = QualityMode.High;
perlin.Seed = 8;

//Create our 2d map
Noise2D _map = new Noise2D(CHUNKSIZE_WIDTH, CHUNKSIZE_HEIGHT, perlin);

//Get a section
_map.GeneratePlanar(left, right, top, down);

GeneratePlanar is the function to call to get the sections in each direction that will connect seamlessly with the rest of your world.

I've used the above method, and it works great.

Another alternative is to generate noise using libnoise libraries. You can generate noise over a theoretical infinite amount of space, seamlessly.

Take a look at the following: http://libnoise.sourceforge.net/tutorials/tutorial3.html#tile

There is also an XNA port of the above at: http://bigblackblock.com/tools/libnoisexna

If you end up using the XNA port, you can do something like this:

Perlin perlin = new Perlin();
perlin.Frequency = 0.5f;                //height
perlin.Lacunarity = 2f;                 //frequency increase between octaves
perlin.OctaveCount = 5;                 //Number of passes
perlin.Persistence = 0.45f;             //
perlin.Quality = QualityMode.High;
perlin.Seed = 8;

//Create our 2d map
Noise2D _map = new Noise2D(CHUNKSIZE_WIDTH, CHUNKSIZE_HEIGHT, perlin);

//Get a section
_map.GeneratePlanar(left, right, top, down);

GeneratePlanar is the function to call to get the sections in each direction that will connect seamlessly with the rest of the textures.

Of course, this method is more costly than simply having a single texture that can be used across multiple surfaces. If you are looking to create some random tileable textures, this may be something that interests you.