One of my wiki members is doing a 4e to 3e conversion, though he's been slow the past week or so. You might want to check it out, even though I don't think he's done anything with rituals yet.
We're using the Bo9S, so martial characters have impressive abilities, and generally more mobility in our game. It generally feels more mobile, and more spectacular, even if damage output may not be that much better compared to "charge and power attack, full attack, full attack, full attack cleave".
What I want to see from 4e is the non-biological aspects of race become feats and the races balanced accordingly.
For rituals, what about using incantations from Unearthed Arcana?
For skill challlenges, what about starting with complex skill checks from Unearthed Arcana and modifying it from there?