I have found courses to learn six modern Indian languages. The people at the Central Institute of Indian Languages (CIIL) have designed these courses. The scholarship of the institute is undisputed. You can safely jump into their learning materials and come out conversant in the language of your choice.
These courses are available for Assamese, Bengali, Gujarati, Oriya, Marathi, and Kannada.
Bhartiya Bhasha Jyoti hosts courses for five languages, other than Kannada. The language of instruction is Hindi. The course for Kannada is found on this web page: CIIL Learn Kannada. They teach through English here.
