ArmyCalc is a new Open Source army construction tool that has recently been made available to the public.
From their announcement:
ArmyCalc is an Open Source project that have been developed for the last 2 years. Recently the beta stage was finished and everyone is free to register.
Besides of online editor ArmyCalc has also a downloadable application that can be used for creating army lists.
For now only Infinity armies and few WFB ones are available but new can be added by users.
You can test ArmyCalc here. After free registration you will be able to save and organize your armies.