It's good to see though that the first result of this search in Google is a page explaining why alot is not a real word.
From: http://www.wsu.edu:8080/~brians/errors/alot.html
Perhaps this common spelling error began because there does exist in English a word spelled “allot” which is a verb meaning to apportion or grant. The correct form, with “a” and “lot” separated by a space is perhaps not often encountered in print because formal writers usually use other expressions such as “a great deal,” “often,” etc. If you can’t remember the rule, just remind yourself that just as you wouldn’t write “alittle” you shouldn’t write “alot.”