In my prep for applying to medical school, one of the resources that have been the mostly helpful are premed forums. Members can assess your chances, they can give you advice on everything from best courses to take to informing you on changes to med school policies, their personal success stories (I especially like reading the stories of other non-traditional applicants such as myself) and they often even post their stats (GPA, MCAT score, what extracurricular activities they had etc) and whether they got rejected or accepted to med school with those stats. Its definitely useful because med schools usually post averages and highs/lows only so its hard to tell what individual accepted candidates really looked like. I even found a great Organic Chemistry tutor via a forum.
To be honest, though you really have to take EVERYTHING said on the forums with a grain of salt. There are trolls, people who just don't know what they are talking about (like high school students) and people who are just speculating. At the end of the day, NONE of them are on admissions committees and really don't know for sure what the admissions committees are going to be looking for and prioritizing.
And forums can be a MAJOR time suck. Its hard not to get involved in debates that sometimes spring up and hard not to be very judgmental (i.e people with a terrible GPA in their first 2 years announcing that they will for SURE get a 4.0 for their last two years, or worse, people who compare themselves to Einstein or other exceptional individuals) and just telling people to get a reality check.
I often need to take a break from the forums because I find when I've been spending too much time on them, I end up anxious and just negatively affects everything from my motivation to my mood.
But all in all, they are very useful and I'd recommend them to anyone pursuing medicine, whether they are high school hopefuls or other old non-trads like me.