Rachel Adler, in chapter 5 of her Engendering Judaism, details a wedding ceremony meant to be a “lover’s contract,” based on shutafut, a traditional model for partnership (usually business partnerships) rather than the traditional model of marriage.
I don’t have the book handy–it’s in another country–so I’m not going to write about the ritual’s mechanics in detail. If someone does, feel free to email me; otherwise, anyone interested should just check the book for oneself.
It’s not clear to me whether a couple using her ceremony would be legally obligated as a business partnership (and what that might entail). I don’t know enough about hilchot shutafut to know how, halakhically, one might end a partnership. I suspect that there’s more than simply walking away, but this isn’t something I’ve studied in detail. Anyone who knows, please email me or comment here!
ADVANTAGES: Does not require a get, is fully egalitarian, is same-sex marriage friendly, has a historical connection to Jewish ritual history (ie, it’s not a ceremony invented whole-cloth). Is possibly binding legally.
DISADVANTAGES: It’s not kiddushin, so halakhically one is not fully married (I recognize that, re: the get issue, this is a plus for some people), it doesn’t “feel” like the traditional ceremony. Unclear (to the author of this site–I need to go learn this) what needs to hapen to “unbind” a partnership.
The Kiddushin Variations 
We used Adler’s ceremony as the basis for our wedding five years ago, loving the idea that it is a halachically-valid form of relationship, but gets “outside” the gender bias in traditional kiddushin. For the record, we WOULD use a get in the event of divorce, simply because something that begins with a Jewish ritual ceremony needs something equally weighty to end/change it.
One of the significant differences between kinyan and brit ahuvim is the notion of the “shutafut” or partnership: instead of the groom giving kinyan as a sort of bride-price, both partners put something of value (in our case, our rings) into a pounch and lift it up together to symbolize joint investment in the new relationship. This is a wonderful metaphor and beginning for an egalitarian Jewish relationship, and I know that it set a psychic imprint on us and our witnesses as to how our lives would continue together.
It was also important to us that any ceremony we used be equally accessible to same-sex couples, so as not to perpetuate a religious discrimination. We have, in essence, a legally binding exclusive family partnership – a Jewish civil union.