The Day Sling from Aer is a stylish smaller sling with a bunch of organization for minimal daily carry.
Other Bags to Check Out:
Smith the Roll Pack from Millican is a perfect eco-friendly rambler for daily adventures that's built excellently, has plenty of room for your stuff, but still looks good when it's not totally full.
The Everyday Messenger from Peak Design is a delightfully innovative messenger, with the capabilities to be used as both serious office bag and adventure photography/drone bag.
The Weekender Meeting bag from North St. is an excellent little slimline daily carry bag. Built by hand in Portland, OR, with great materials. Attaches to the larger Weekender Travel Bag.
An extremely solid everyday backpack suited for carrying lots of gear or compressing down to a minimal daily carry haul. One of my favorite all-around bags.
Trakke make some of the most understated and thoughtfully conceived daily carry products. This bum bag is no exception.