Trello + Agile = Pain. It lacks time tracking & estimates. It has no agile features like burn downs. It doesn't even have reports :(
agileTrello attempts to solve that. It use a convention to inspired by ScrumForTrello where you place estimates & actual times in the card header. Estimates are wrapped in paranthesis () while actual in brackets [].
agileTrello adds to that by supporting planned/goal story points in the column name & the ability to provide config through a dedicated configuration card.
This is a tool I use and it is sort of built for my needs, but I am trying to make it versatile. It is very much a work in progress.