Here's the first article, Potter's Hermione Granger is a Pop Culture Anomaly.
And the second, An Unabashed Love Letter to Ginny Weasley.
(Luna Lovegood doesn't tend to get a lot of attention, but she is one of my favorite characters in the books and I think her character is as hilarious as she is loyal and wonderful and I wish more people felt the same way.)
Thanks to Geena Davis and her wonderful Institute, we're getting a lot of unprecedented research about how... the media is really sucking at putting girls in good roles. Or having girls in the media at all. Having role models in popular media is especially important to children, and when girls watch movies and TV shows in which boy characters are the leads and get to do all this cool stuff while girl characters get a couple lines and are generally relegated to the background, what kind of message do you think that sends to young girls?
Looking only at the list of Pixar feature films (which are hugely popular movies with children), let's see how the gender breakdown works:
Toy Story (1995) : male characters, very little female presence.
A Bug's Life (1998) : male hero. Female ants sexualized.
Toy Story 2 (1999) Mostly male characters and heroes, introduction of Jessie, a supporting female character.
Monster's Inc. (2001) : Mostly male characters and heroes. Little girl is subject of rescue missions, and Mike's girlfriend is generally comedic relief.
Finding Nemo (2003) : Dory is a funny female character (hooray Ellen Degeneres)! But only significant female presence in the movie, which is mostly male-dominated.
The Incredibles (2004) : While the father is the main character, the mother and daughter have significant roles and are generally good, smart, female role models (and superheroes!).
Cars (2006): Mostly male characters. One female character as a love interest. (Side note: Cars have love interests? This was a weird movie.)
Ratatouille (2007) : Mostly male characters, female supporting character as love interest.
WALL-E (2008): Mostly male characters, EVE is the only female presence and love interest. (Okay, this movie had my roommate and I weeping and declaring how this was the most beautiful love story of our time. Somehow robot love is more believable than the love of anthropomorphic cars.)
Up (2009) : Mostly male characters, one female character as the dead love interest.
Toy Story 3 (2010): Still mostly male characters.
Popular children's and young adult novels often follow this same trend. There are some notable children's novels with strong female heroines (Tamora Pierce books are notable fantasy novels with female main characters, Ella Enchanted and other Gail Carson Levine books also are fantasy novels that feature strong female main characters. Side note: Ella Enchanted remains one of my favorite books ever and I love how it turns the classic Cinderella story around into something empowering and awesome. The movie was a disappointment. When I was a counselor to 10 and 11 year old girls I read to them from Ella Enchanted almost every night and they loved it.), but the sad fact is that it's notable when there are books with strong female characters. While Hermione and Ginny are supporting characters in the Harry Potter series (well... Hermione can be counted as a main character I guess), they represent some really wonderful literary role models for boys and girls alike.