Tip 102: take up a hobby that doesn't cost a lot.
I was a landscape photographer until I broke an ankle, tore and detached a few ankle tendons. It was my job and my passion, once you have a camera you can get out into any location and find great and dramatic landscapes, however after the injury walking causes too much pain and I needed to find something else that didn't cost a lot of money as I was trying to save as much money - the reason for starting the money saving sites.
I started bird watching, it's a big thing in the UK and can cost a lot of money if you buy all the expensive gear top of the range binoculars, telescopes, long camera lenses etc. To keep costs down I do a lot of garden bird watching and although I've always had an interest, here's a few of my photos from Sydney: https://plus.google.com/+Wbist/posts/DLBYTHEU1qU - I started taking records of the birds in my garden, it means I don't have to walk far and I've found it interesting... Obviously not for everyone it really is the train spotting of the wildlife world.
There's probably 100s of free or very cheap hobbies, or even a free to play sport.