(Edited July 10, 2018 to update link.)
I discovered this site some time ago and have used the Comprehensive Aramaic Lexicon site it as a reference before, but P. J. Williams on Evangelical Textual Criticism reminded me today that it’s nice to link to and recommend resources such as this.
You have to be ready to do a bit of work to find what you want but there are some wonderful resources, including lexical information and texts linked to a lexical breakdown. For someone like me, who uses Aramaic occasionally, and thus lacks some of the best library materials, this site is extremely helpful.
Spend a little bit of time scouting around and looking for the options. The information on how to use it is there; it’s just not always obvious.