OK, maybe it's an old trick, but I thought I'd share this secret I used once.

If you take a cotton cloth (like a baby diaper) and lay it over the stain and then take a hot iron and place the iron over the cloth and just hold it there for a bit, the heat from the iron will enable the cotton to pull the stain from the carpet.

I've seen this work on ink, dirt, wine, etc. -- you can try it, but don't hold me responsible if it doesn't work. It did work for me, however!

And if all else fails call a carpet expert. I recommend ZEROREZ at 582-5000. They are amazing at getting out stains, odors and everything! They cleaned my carpets and it was incredible!