I use a lot of golden creeping Jenny, which is also called creeping Charlie, and moneywort, (botanical name Lysimachia nummularia ‘Aurea’), in containers. It is incredibly easy to grow, it's beautiful and drips over the edge of pots, giving a lovely elegant look. It can add a great pop of color--the leaves can vary from yellow, when in full sun, to a fabulous chartreuse when located in partial shade.
While creeping Jenny will flower, the flowers are small and pretty, but fairly short lived, so it's mainly grown for it's foliage. Happy in full sun to part shade, it will tolerate fairly wet conditions. Don't let it completely dry out.
Creeping Jenny is also very easy to propagate by rooting in water. I have a patch that grows as a ground cover. In the spring, I dig up a bunch and throw it into a big plastic bin of water. It roots quickly and then I have as much creeping Jenny as I need for all of my summer containers. I also dig up chunks, with soil intact, and plant it in containers as well. Creeping Jenny is hardy from zones 3-9 so can easily be overwintered in an unheated garage.
CAUTIONARY NOTE: Creeping Jenny is considered to be an invasive plant, in some places, though the golden or 'Auria' varieties are not as invasive as the green. While it's not banned, even if you plant it in containers, be careful when dumping your containers at the end of the season. Be aware that it can quickly get established and grow like wildfire. Also, I have had creeping Jenny sneak out of a container--dripped so far over the edge of the container that it rooted and spread into my lawn.
Photos of creeping Jenny in containers: