No, not hacks in _that_ sense. More, here are a number of ways to hack your very own grey cells or (I guess) someone else’s*.
Remember that your brain is more like a computer than you might, at first, think. It takes a series of inputs (generally from your senses), does something with them (such as analysis), and returns outputs (such as decisions, or sensations, or suchlike). Which also means that you can mess with it :P
Which have you tried? Which is your favourite?
Related posts: Distorted internal body maps, anyone?
* Please note that this author only supports neural hacking if it is carried out between consenting adults.