save color channels as separate files

You may want to give this article a look:

http://www.creativepro.com/article/photoshop-how-to-printing-separations-in-color

Basically after using split channels, you will then convert each grayscale channel to duotone/monotone mode assigning a color to each channel.

Try Channels > Split Channels.  You will get a grayscale file of each channel ( do the "split" on a copy so you will have the original to go back to in the future ).  You could "Place" the .tiff in Illustrator and paint it a process color there.  Then, export that individual file as a .tiff or whatever.  This works on a CMYK file, but should work for an RGB file, too.

You could do it manually...  Select all, then choose a channel in the Channels panel, then copy.  File - New, grayscale, paste, and flatten.  File - Save As, and there you go.  Repeat for each channel.

If it's something you need to do a lot you could automate it with an action.

-Noel