I have discovered some fun, easy techniques from looking at house painting books. Some of them are about faux techniques and some on textures. Take a look the next time you are in a bookstore.
If you try these techniques, there is nothing saying that you cannot combine any or all of them. Don't forget that you can layer. The bottom of a texture can be as interesting as what is on top or inbetween.
Mottle with a rag
Use cheesecloth as an applicator - use it as texture on your surface- remove before dried.
Dry brush - cut off some of the bristles on your wide, cheap brush to get uneven coverage (my idea).
Use a 2 part roller - remove sections of the roller or carve designs in it. You can also use those small, foam rollers for this on smaller surfaces.
Pounce a feather duster with some paint on it. Great with Lumiere paint or a little mica powder on the ends of it.
Dry rag in glaze
Twist a rag lengthwise - roll in paint and then roll on surface
Use a trowel and just apply to random areas for texture
Press some burlap into the surface, use a trowel or brayer to press in, and then remove - use fresh pieces so you get an impression of the texture. You can also make use of both sides but trowel or brayer will get yucky.
Frottage - I have not done this yet but it seems interesting. You can have the same color base or you can have different colored blocks. Crumple up some newspaper - the kind where the print comes off. One of our newspaper advertises that the print does not come off on your hands. Don't use that one. Open up the newspaper and lay to the side. Apply different colors of glaze to your background or block. You might want to work on small sections so the glaze does not dry. Press the newspaper into the glaze - print side to glaze. You might want to brayer or smooth with hand. Check for ink transfer. Peel off. Don't let the glaze dry with the newspaper on there. If little pieces stay behind, then you have some interesting texture.
If you are interested in simple background techniques, then I recommend Paint Effects Manual by Kerry Skinner. She has great step-by-step instructions. It is meant for house paint but you can substitute acrylics very easily.
Let me know how your techniques turn out! Hope this gives you some creative ideas to get through the holiday season.