If you have the Tooche.B slider theme, and possibly others too there is an easy way to change your background daily. You also need to have iFile in order to do everything form the phone without the need to SSH in. The background file is called Background.png and is in the root of the theme folder. So if you create multiple backgrounds for the theme you will need to initially SSH in to the phone and put them all in the root of the theme. I named mine Backgound-1, Background-2, etc. So then all you have to do when you want to change the background is open iFile and go to the theme click on the Backgrounds and use the Image Viewer in iFile to look at the file so you know which one you're putting up. When you're satisfied just change the name of the Background.png file to whatever number in the sequence. Then change the file you want to set current to Background.png and respring Voila. I'm sure you could do it with other slider themes too but it is dependent on how their files are structured.
Thanks, Iphueria - I have a 3g (as you know) and I don't have any backgrounds but I'm going to save these instrutions for when I get my iphone 4 as soon as my contract is up (in about 2 monrhs).
You know what would be sweet? If you added 7 backgrounds, then tweaked the theme code so that it used a new background for each day of the week. I actually don't think it would be that hard, except maybe for getting them to rename automatically.
You read my mind except the coding to do the switching is what I wouldn't be able to do. The naming I think would be easy because you would just separate them by folders like 1,2,3.... and then in each folder has the Background.png file so then it would just be using the folder each day.
