A friend has suggested eggwhite as a fining for a beer brew. Is he pulling my leg? I'd like to know if anyone else has tried it before I find out either way!
Egg whites have been traditionally used to clarify wine and remove bitter and/or tannic compounds. See the answer to the first question in this article. Wikipedia also mentions egg whites as a traditional fining agent.
That being said, you're probably better off using a fining specifically designed to clarify beer. Isinglass, gelatine and bentonite all work well. This Beer Smith blog entry outlines the uses of generally available fining agents.
Egg whites are positively charged, so it will attract negatively charged particulates (e.g. yeast), therefor it should have some degree of success in clarifying your beer after fermentation completes.
In order to use egg whites, you have to fully separate the egg white from the yolk (one egg for a 6 gallon batch), add it to a 100 ml of salt water (by adding 0.15g or a pinch of salt), whisk or blend until the solution is smooth, skim any foam off the top that will serve no purpose other than to float atop the beer, and add. It is recommended for wine to be removed after 14 days, so I'd imagine you would want to do the same with beer.
If all that seems a bit excessive if not dangerous, adding potentially contaminated raw egg to your beer (which it should), go purchase yourself a $2 bottle of gelatin and use that instead. There's a reason not a whole lot of people use egg whites now a days when a simple gelatin mixture in 150*F solution will work just as well if not better, and safer.