tl;dr: find a way to let new visitors participate without cluttering the site with non-answer answers
So, we've long struggled with people new to Stack Exchange answering questions with "me too!" kind of messages. They leave an answer because their reputation score is too low to vote or leave comments, but not too low to leave an answer. Desperate to participate, and not knowing how Stack Exchange works, they leave an answer. And we all know what that leads to.
How about a big, bright exclamation point next to the question, similar to the vote buttons, that lights up when clicked? It'll be labeled something like "I have this problem too!", will not require any rep points to use and, when clicked, also increments a counter which is displayed with the question. ("123 other people also have this problem")
After clicking, perhaps the user could also be guided to following the question, either by favoriting it and/or subscribing to its RSS feed. Registering too, if they haven't already.
The flag wouldn't do anything else. No reputation points or badges. It might prompt the more magnanimous among us to answer those questions that have high "me too" counts. ("If I can answer this question, I'll help over ten thousand other people!") Which might not be such a bad idea. Haven't you ever spent time and energy on an answer and felt like you were probably just dropping that work into a black hole?