One of my bags is a LowePro Adventura 170 small shoulder bag. Fits a large DSLR, two lenses, and some accessories great. But I need something with similar capacity that holds a tripod and is a little more secure if I'm on a bike. So I'm thinking a small sling style bag may be a good option. I already have a big backpack and don't really want another backpack. These seem to be the most popular.

ThinkTank Sling O Matic http://www.thinktankphoto.com/products/sling-o-matic-10.aspx
Kata 3N1 http://www.kata-bags.com/Bag+Families/3N1+Family/3N1+Family/15524933
LowePro Slingshot http://www.lowepro.com/slingshot

Are there any others you've used that I should be taking a look at?

My experience: I used a Lowepro Slingshot for several years. I quite liked the usability of the bag - you can access it without taking it off. But - and it's a huge 'but' for me - I could not wear it for long periods of time. I do a lot of hiking over rough terrain and whenever I carried this bag for more than an hour or so, my shoulder got extremely sore and I couldn't wear the bag any longer. I switched to a Lowepro backpack style with a tripod carrier and I'm much happier even though the new bag is considerably heavier and more difficult to use.

Edited for spelling