So, this one has definitely been inspired by the recent relocation of my studio to home. I was able to work before on my iPad but it definitely helps having the full setup!
Some of the most useful practice tools that I've aquired over the years have usually been some sort of home recording setup. Whilst home recording is nothing new the accessibility of this has become within reach of more people with the rise in popularity of phones, tablets and other mobile devices and the apps that can be used with them. In truth, all you really need is something with a microphone and the ability to record, so Voice Memos on the iPhone is a good simple example of something you could use.
When playing and practicing a guitar player can percieve the sound that they are making in a much different way than it actually sounds to someone listening independently. Whilst practice and experience can help to improve this it's always worth doing this from time to time to make sure that the sounds that you are making are actually what you want to make!
It's useful for gaining perspective on things. So, is something actually as good as you think it is? Is that strumming pattern in time? Does that improvised guitar solo make musical sense? Alternatively you could be giving yourself a hard time over something that actually sounds quite nice. Either way, being able to record and listen back is very important for your musical development.
Another great advantage of recording yourself is that you can track your musical progress and development. Listening to a recording of yourself from 6 months ago can be a real boost when you feel that you are not making progress.
In this day and age it's so easy to get started. Make it your habit to record yourself playing at least once a week. Keep a recording diary of your playing and listen to yourself improve!