There's a lot of ground to cover. We're roughly a month into the new season, so let's get this started.
Each of the five girls has a character single on the way, featuring an original song and a solo version of the OP.
Two character songs have been announced, more might possibly follow.
Uta no Prince Sama
It's a show about music, it would be weirder if it didn't. But, yes, it does. Looks like the main characters all get a single.
An album for the maids has already released, with two CDs, each containing two songs apiece, on the way, covering other characters. The first CD has Alma and Ruri. There might be more, but not much is listed yet.
Yes, more are on the way.
A drama/character song CD has already been announced, so it'll have one song at least.
Kaitou Tenshi Twin Angel
Not likely at this point, though the franchise already has a fair amount of music built up over the years.
Yes! All eight main characters, in the Amusement Club and the Student Council, plus Mirakurun, are getting their own character singles. Notably, the Amusement Club's work in their leitmotifs you hear during the eycatches.
A drama/character CD or two has been announced for this show as well. Really, there are very few shows that don't have one this season.
This one's tricky. Technically, the iM@S franchise already has several gigabytes worth of songs released, that are being used in the show. As it turns out, those songs will be compiled onto albums released throughout the year, making it much easier on people who started with the anime. They're still not exactly "new" songs though.
A character song album is on the way, covering the major characters. (The female ones, at least.) Standard form here.
A single for Hideyoshi, two character singles that revolve more around concepts than characters, and an "Akihisa Harem CD" are all on the way, as well as whatever milktub's doing. None of them is a standard character song album like the first season, but the show has no shortage of music.
Itsuka Tenma no Kuro Usagi
Two albums with three songs apiece, collectively covering pretty much all the major characters.
Three albums with two songs apiece (though the final volume is for three characters), covering nearly everybody as well.
Two albums (team MAJIYABA and team HIRAMEKI), each with songs from four characters. This includes the protagonist and his best friend, a rarity for shows of its genre. Also, Ran is on the first CD. Make of that what you will.
Not likely to get character songs at this point, though I wouldn't rule out the possibility entirely.
Bibliotheca Mystica de Dantalian
Also unlikely, just from the tone of the show.
Odds and Ends
Nichijou has character songs announced for Sasahara and Misato, one for the Last Five People, and a "Mai Pace" CD. Strike Witches 2 continues to have its character songs delayed, but they're on the way. Denpa Onna's included with the DVD character songs were pushed back. Milky Holmes has a third album for sale.