I need (at least 10) recipies and menu ideas for a low-budget
Valentine's Day-themed company cocktail to be attended by 400 guests
this Friday afternoon. The cocktail items should include sweet and
savoury and be simple & cost-effective to prepare and serve.

Hi,

Recipes for 400 are not easy to find. 

This site may be all that you'll need
http://members.tripod.com/~lotsofinfo/ 
Their Easy Cold Buffet for 100 can be found on 
http://www.angelfire.com/bc/incredible/coldbuffet100.htm

The Google directory for Quantity Cooking has a good selection of
recipes to feed large numbers of guests
http://directory.google.com/Top/Home/Cooking/Quantity_Cooking/

The DMOZ entries for quantity cooking should give you some good
recipes
http://dmoz.org/Home/Cooking/Quantity_Cooking/

However, you can use any recipe - the rule is to increase the
ingredients for a simple recipe to make it serve as many as you need.
So if you have a recipe for 8 and you need 400... multiply each
ingredient by 50 (400/8 = 50) So instead of a quarter pound of butter
or margarine, you'd need 50 x 1/4 = 12.5 pounds...

Sit down with your recipes and a calculator to convert them before you
start.

I hope you have the facilities and equipment to handle this type of
work, cooking for 400 is moving into professional catering.

A hint for making any dish more eye appealing for Valentine's Day is
to add red food coloring. It doesn't effect the taste and can be added
to whatever liquid measures you use to make sure that the foods on the
menu don't wind up being soggy.

This site has some good decorating ideas
http://www.reasontoparty.com/valentine.htm

Ladies Home Journal covers all the bases
http://www.lhj.com/lhj/category.jhtml;jsessionid=SNQ1IVTJ122S1QFIBQPSBHWAVABCIIV0?categoryid=/templatedata/lhj/category/data/ValentinesDay.xml

This site gives some good advive for pre-party planning
http://foodandwine.netscape.com/invoke.cfm?ObjectID=E9AFF3D2-58E2-4553-849DE67D060E1199

A good cocktail party menu...
http://www.southernfood.com/menuofweek/menu041801.htm

Some sites that focus on Valentine's day menus are:
http://gold.zidaho.com/sharedcontent/features/food/generalstories/020503ccfoodeditors.22fc1cbe.html

http://gold.zidaho.com/sharedcontent/features/food/generalstories/020503ccfoodcranberry.264c9bda.html

http://www.foodtv.com/holidays/ho-g1/0,1948,,00.html

http://www.southernfood.com/menuofweek/menu020102.htm

http://www.fabulousfoods.com/holidays/vday/vday.html

http://www.cooking.com/advice/adarticle2.asp?id=135&seq=2

http://www.starchefs.com/features/valentines/html/index.shtml

http://www.party-tip.com/index.php?page=parties/food-appetizers&id=1&ps_session=e053449b0c171b7f7d49a8c47ab46c2c3e469a3c

http://eat.epicurious.com/holiday/valentines_day/?/holiday/valentines_day/main.html

search terms: 
cooking recipes "large groups"
recipes quantity cooking 
Valentine's Day cocktail party menus

If you would rather have me go through the sites and pick out ten
recipes, just post the clarification.

Since you are the "chef" I thought you might want to browse through
what is available for the dishes that you would like to serve. If you
want just the ten suggestions, I'd be glad to sort through for the
ones I'd serve.

Cooking for 400 is a big job - but sounds like a lot of fun!
bcguide-ga

Quick and impressive is a thin slice of smoked salmon on rye, a dollop
of sour cream or horseradish and a couple of capers. Pear, prosciutto
and blue cheese is another good combination.