Cryophytum (ice plants) cascade in a variety of bright colours. I think they are banned to sell now but plenty of people have them in their gardens to get some
Arctotis - wide variety of colours, pretty gray leaves
aubretia (aka aubrieta or aubrecia) - trailing evergreen with pink or purple flowers
lobelia - upright and cascade in variety of colours
begonias - flower profusely
portulaca (sun plant & drought tolerant) variety of colours. Die off and then self seed everywhere
alyssum - hardy white and pink. Self seed like portulaca
pansies
violets
Celosia (cockscomb) - look like flames in red, yellow, orange and pink
look through plants in nurseries or Warehouse as labels will tell you what conditions they require. Look for the mass blocks rather than individual plants.