for some reason, i'm really excited about this thread - perhaps because i feel i have more experience to offer in this area than in the 'hard' skills area of rewilding.
urban scout, i'm not sure if you're asking specifically for grieving rituals around death, but i see grieving as something that needs to be done on many levels.
a specific ritual i have participated in and facilitated is something called the 'despair & empowerment' ritual. http://www.rainforestinfo.org.au/deep-eco/truthm.htm
it was created by a woman named joanna macy and developed into further work that centers around sharing deep feelings in circle, and moving through the feelings to a place of connectedness. i have had great experiences with each circle as have most of the people i've talked to who participated. if you have any questions about it, i'd love to share more - i think it's pretty easy to learn (there's lots of material available on this work) and easy to bring to your community.
on a more macro level, i feel its important to add some context to deep feeling work. this is an area that i feel is a huge blind-spot, not only for the dominant culture, but also for most progressive, radical, alternative etc communities. my experience is that learning to feel deeply, fully and expressing this in a safe and connected way is a prerequisite for healing to happen. in the civilized world, we bear many, many, painful scars, particularly from childhood, where humans are especially vulnerable to mal-treatment (i think here of the continuum concept and the trauma that occurs when we have experiences that are outside of our continuum). as a species, humans have a fairly long period as children of being vulnerable, dependent and with fairly specific needs for healthy development. this leaves us much more susceptible (than a turtle say who is independent from day 1) to emotional/psychological damage. i believe that most tribal peoples represent human potential when parenting/childhood is done properly - according to our real needs.
there's a line from 'against civilization' (edited by zerzan) that goes something like 'the birth-right of primal peoples is what zen masters spend their entire lives searching for' - what i love about this is that it says that in our undamaged state, we experience what some describe as enlightenment (i don't much like the term because it's inherently contradictory, but to use the general sense of it).
i have been doing primal therapy for about 2 years now (which i found out about after reading continuum concept and became curious about the work that jean got into trying to heal those who had non-continuum childhoods) and the essence of it is connecting to the feelings that are there, and expressing them. primal refers to the early childhood scars that we carry with us and that drive much of our current day behaviour. by releasing those feelings, we are freed from their hold on us.
soooo...to bring it back to grieving (sorry for the long tangent, i just get excited about this stuff), i think those of us reared in civilization have much to grieve for (loss of tribe, territory, functional parents, elders, separation from mother etc etc) and it is critical that we find safe, healthy and effective ways to deal with these feelings.
i think it's important to do this work both in a community setting, and in a more private setting (ex. with a therapist). the community setting is perhaps obvious as to it's importance, but i think the 'therapist' piece is equally essential because certain needs are much harder to deal with in a community setting and require experienced guides to support you. my experience has been that in a community setting, i am able to move through more surface level feelings and deal with issues related to inter-personal relations, but that i have gone much deeper with my therapist because in that setting i have the time, safety and focus to go where i need to, and because it is a relationship that continues to deepen and develop more trust, which is essential for letting down defenses to get to the feelings.
i think a lot of therapists are probably pretty messed up people, and people who are into hierarchical, control style work, so this isn't a blanket statement of find any therapist you can (nor that everyone needs to by any means). just that my experience of therapy has been incredibly healing and grounds and informs my life.
phew! hope that wasn't too much of a rant...would love to hear others thoughts on the feeling/grieving topic.