www.mdbg.net -my go to chinese dictionary. Usually has what you're looking for, and has good enough definitions that I can use the words correctly when writing.
www.chinesepod.com -Used to be free, but now it is paid. But still has really great lessons, including vocabulary, sentence structure, listening, reading, and questions on topics that range from traditional medicine to owning a car.
Wenlin Software- available at www.wenlin.com. Sort of a combo of a dictionary and a reader. You can copy and paste texts into the window, and it assists you in reading with a scroll over dictionary feature. This is a great piece of software- seriously. You can get a free trial, here.
Fluent U- Fluent U is really fun, it's a database of music videos, movie scenes, etc with Chinese/English Subs. I like to use it before I go to KTV to brush up on my Chinese songs! It breaks the video down word by word, including questions to help you get the vocab down.