Here are some of my favorite bags. (some of these I own myself, some are recommendations from BWing friends and some are on my personal Christmas list!) Spam me in the comments with your faves!
My #1 pic is the JuJuBe Quick. It is basically a wristlet but it is big enough to hold a cloth diaper (or disposable) a thin wipes case, my wallet, phone, and keys. What else do you need for a quick trip? I can clip it to the rings on my ring sling, the waist of my mei tai or Beco, or my belt loop if I am wrapping. I can also clip it to the grocery cart or a stroller if Sophie is riding that day (which is usually the case since at 3 years, she won't let us wear her much anymore!) I have two of these, I love them that much! Cost: $15
I also love the JuJuBe Light. It has an adjustable strap that ties wherever you need it which is great since you can thread it UNDER a carrier and tie or wrap it around your waist or whatever you need. It is reversable so you actually get 2 bags for the price of one. There are deep pockets and the slick fabric is easy to wipe down. It holds a deceptively large amount of stuff for such a small bag. It is super lightweight (don't you HATE bags that weigh a ton before you fill them?) and there are tiny crumb holes in the bottom so sweeping out the crushed Cheerios and Goldfish that accumulate in the bottom of my bags is a breeze! Cost: $35
DH swears by the Ergo Backpack. It attaches to his beloved Ergo and he uses it even when I wear the baby. It is manly enough for him and carries a TON of stuff. He loves all the pockets and compartments. It is compact enough for my 7 year old to be able to wear it as well. Cost: $48
Bags from Brooke Van Gory Designs.
These bags are recommended by my fellow BWing friend Megan. I love her designs and must get one of these ASAP!
I can't read Polish but one of my favorite babywearing mamas (Erin of Wrapstar) posted about these bags and now I dream about getting one. I couldn't post about bags without sharing this link!
Another of my favorite babywearing mamas (Jillian from PaxBaby) carries these adorable little pouches. They slide on to the waist strap of your mei tai and I assume it would work with a SSC as well. I highly recommend Jillian so if she recommends these, I do too! Cost $25
UPDATE! I got one of these recently and it is super cool! Just as awesome as I thought.
I have heard nothing but wonderful things about the OnBag. It is made across the pond and like the Be Light, it ties on. Unlike the Be Light, it is large enough to use for an all day outing. They are not the easiest to find since they are sold out on their website but the good news is that there are babywearing vendors like Birdie's Room who carry them and OnBag includes DIY instructions on their website. $144 CAD at Birdie's Room