I am so with you on the amount of STUFF that is given at baby showers. Holy cow! A relative of mine is having twins and the mountain of gifts when she was finished unwrapping was as high as my head. and a good 6-8 feet wide.
We also co-sleep, breastfeed, cloth diaper and babywear, of course, but I still found my shower to be extremely helpful. And I had three! (Family, my work, dh's work). They wrote that I would be cloth diapering/breastfeeding in the invite so no one brought formula or sposies. I didn't know what I was having so I didn't get a ton of clothes--people weren't that excited about buying green and yellow. I only got one toy and I sold it on eBay
I kept a pack of Gerber prefolds for burp cloths and sold the rest on eBay. I returned some duplicates, sold the gift cards, and used the cash to buy 2 dozen bumGenius diapers.
A few other things I got that were helpful:
Breastmilk storage set (I did pump from time to time)
Rocking bouncy seat
waterproof covers for twin mattress and full mattress
car seats (2)
Tylenol/Motrin (we do use from time to time as a last resort, ymmv)
baby washcloths---(make great, great great cloth diaper wipes!)
Can't think of anything else off the top of my head but I guess my point is that even co-sleeping, breastfeeding, etc you may find a shower helpful for the miscellaneous so you can focus on the clothes, toys, slings, and cloth diapers that can really add up. And if you register at Pottery Barn kids they have a nice block set, a wooden activity cube, and a few organics. Maybe when people see what kind of stuff you registered for it will spark some ideas and they will see you like the classic/organic stuff. Worked for us--I got some beautiful organic clothing and stuffed animals and blankets from purebeginnings.com