My mom has been picking up these sample Gain "Pods" and scent boosters (like Tide Pods / boosters, but from Gain) from Lowes.
I usually only use them when I'm running low or completely out of my normal detergent (Tide Cold Water), but have found myself to be using them more frequently because I love the fresh scent they have!
I use the scent boosters primarily with towels and bedding as the scent is awesome and lasts quite a while. I don't trust scented things with normal clothing as one of my kids has sensitive skin and I'm afraid it'll set off an allergic reaction (hasn't yet, but you never know with products these days).
We don't normally have stained clothes in our family (at least not like we used to when the kids were infants) but we do laundry nearly every day... hence why we switched to cold water. These Gain pods and boosters worked well in cold water though I'm not sure they were specifically designed for it. The first time I used the pod in cold water it didn't dissolve right away and I was worried it'd stain the clothes like the Tide ones do, but so far haven't seen any dye stains.
If they come out with a cold water version and its a decent price I'd switch to the Gain brand.