Have just managed to stave off a cold I felt coming on two nights ago (touch wood). Left choir practice at halftime (ignoring the little voice that said "Just stick it out, another hour or so won't hurt..."), went home & slept for 14 hours; got up and et chicken soup (it's not a myth -- check out Chicken soup is medicine, U.S. scientists confirm), slept some more, et more chicken soup, slept again & today feel all right -- no runny nose or chest infection, huzzah!

I find that home-made (i.e. not from a tin) soup is what does the job for me, although -- according to the article -- some tinned soups performed as well as (or even better than) the homemade soup. Here's the list of brand name soups he tested, in order of how effective they were in slowing the progress of colds and flu (note: "Grandma's Soup" is the home-made (by his wife) soup):

    * Knorr's Chicken Flavor Chicken Noodle
    * Campbell's Home Cookin' Chicken Vegetable
    * Campbell's Healthy Request Chicken Noodle
    * Lipton Cup-O-Soup, Chicken Noodle
    * Progresso Chicken Noodle
    * Grandma's Soup
    * Health Valley 100% Natural Chicken Broth
    * Healthy Choice Thick and Heart Country Vegetable
    * Progresso Hearty Vegetable and Pasta
    * Campbell's Vegetarian Vegetable
    * Campbell's Vegetable Soup with Beef Stock
    * Health Valley Fat Free Garden Noodle
    * Cup O' Noodles, Oriental Nissin
    * Campbell's Ramen Noodles, Chicken Flavor

I found that list here, as well as the recipe for the homemade chicken soup it was tested against (scroll down the page a bit).

Here are a couple more interesting links: Herbal Immune System Soup Recipe: a great cold home remedy and flu home remedy and Chicken & Miso Soup Recipe (haven't tried these myself but they look like they might be well worth a try).

Good luck!