Bellatrix has kipnapped Regulus, I assume since that thread still isn't finished, and is hiding out somewhere.
Ron and Arthur are living at Grimmauld Place with the rest of the Weasleys, being awesome. Neville and Charlie just spiked Neville's birthday cake to make the twins shrink and grow, to get back at them for picking on Neville /anecdote.
Afton, Jason, Draco and Blaise are hiding in a damp forest somewhere much to everyone's disgust
Don't know about Mandy, but poor Penny is probably still sitting in Andromeda's house, and Lily promises she'll come pick up the baby soon...