Here's everything I found yesterday, many of these may be/are DI-able. When I say uptilt/etc without any qualifier I mean light uptilt/etc. I may have missed a few, I didn't really try combos into neutral b for example. These were all on mario btw (I wasn't able to get FF upair to work on mario so I haven't listed it, might be possible though as I didn't try very hard with that yesterday), so there is probably much more that can be done on larger characters. I'm not positive on the X -> grab combos because I didn't have a person with to me really test it.
jab ->
side b
up b - works with command input, but timing is strict
grab?
d-throw ->
up b - DI-able, low %
up air - DI-able, unreliable
uptilt - 0%
uptilt ->
uptilt - any %
jab
heavy uptilt - true combo at higher %, kills
up b - any %, usually sourspot
grab?
dair - 100+%, sweetspots up to 150%
nair - high%, uptilt/heavy uptilt seems better
fair - high%, uptilt/heavy uptilt seems better
dtilt - low%, doesn't string well into dtilt combos
neutral b
dtilt ->
dtilt
strong dtilt
grab?
dair -> (sweetspot hit, hitting opponent lower to the ground is better)
uptilt
jab
heavy uptilt - 10+%
strong jab - 60+%
up b - 10+%
dair - 100+%, hard to sweetspot
fair -> (sourspot hit behind ryu. it pops the opponent right in front of you. like dair but easier after first hit)
fair - 10+%
(heavy) uptilt - 0-70%
jab - 0-50%
up b - usually sour unless DJ first
heavy jab - 0-60%
dair - 60-70%, probably DI-able to avoid sweetspot.
fadc -> pretty much anything (probably the easiest way to start the dair/fair combos)
For the fair combos this assumes you short hop from a standstill. If you try to RAR sourspot fair your opponent, your momentum will usually carry you too far to combo, but I haven't experimented with it too much.