I usually keep this a secret from most of my students! I do tell a few of them so that they can do some extension work.
It isn't that I enjoy watching my students struggle - honestly - but that in the current system they have to learn how to solve questions on their own, unaided and under timed conditions.
However, if a student has genuinely not understood a topic, it is better to get online help than copying someone else's homework the next morning before class!
So, if you've never used this before, try WolframAlpha, the computational knowledge engine. Based upon the Mathematica engine, it is a life-saver for mathematics students.
It will answer most academic questions, from school up to university, and can even give the solution method. Be careful with long word problems and check that it has interpreted the question correctly; if it hasn't, try removing some words and write it in a more algebraic form.
I have also just noticed that they have expanded their Wolfram Problem Generator. You might not think that doing more maths problem could be fun, but if you need extra practice beyond your homework, the Problem Generator will create either one-off questions or a whole worksheet.
This is also great for teachers! The internet is awash with solutions of textbook exercises and past paper questions; here you can generate topic-specific fresh worksheets so you can concentrate on the teaching.
That's it! Check out WolframAlpha and all the various programs and mobile apps associated with Mathematica.
Have fun!