Long time lurker here, but I thought it was finally time to register and contribute.
Some websites that utilize Scene 7 will render out high resolution textures if you change the parameters in the URL. This is very useful for getting specific textures for rugs.
I will use Design Within Reach as a general example. Their website is http://www.dwr.com/
Go to a rug and right click on the thumbnail image and open it in a new browser window
Change the height and width numbers at the end of the url to the size you desire. DWR usually goes up to 3500x3500
Note that some of the textures are better quality than others at larger sizes. It really depends on what was originally uploaded to the Scene 7.