Hi Sally, here are a couple ideas:

-Oxford Picture Dictionary has a great new app for iPads or iPhones that's about $10. It is a fantastic program with hundreds of pictures, vocab, scenes, and audio.

-I've just started a new course that uses the highly interactive online Top Notch English software in combination with my lessons. You can view the course here: http://www.italki.com/course/24495.

-Byki is also another great resource, and it also has a free version

-As already mentioned, Rosetta Stone is excellent (but rather expensive)

There is a famous software called "Rosetta Stone". It makes language learning softwares for many languages now. It might be helpful for someone who has a lot of time, since the lessons or courses are very detailed. You can try it too! ^_^

there are a lot resources in the web, for example:

wilingua.com

manything.com

livemocha.com 

I feel lingoes good,you can try

Yesterday I knew one app for iOS (can be used on web as well) called VOXY, its a good choose, it's very useful and help to understand how to struturate your phrases in english.

Other very good:  TELL ME MORE (you must interact with the exercices to go on)...

SpeakingPal (for iphone/ipad) is the best for me, you can practice all skills through awesome exercices...