I really enjoyed this book when I was at that stage... http://books.google.co.uk/books?id=wUdtVHBr-OQC Really a book about operational research, but covers lots of maths in a really applied accessible way with examples from history (spread of cholera outbreaks, optimal fleet size to avoid submarines in WW2, enigma machine etc.) Lots of exercises, and each section is relatively self contained - so ideal for starting off the kind of short projects you are talking about. Highly recommended...

http://simplefit.org/ This program is based on crossfit principles (worth reading up on) but uses simple exercises that you can do in your house (no equipment). By geeks and for geeks! You easily track your performance and there is a supportive community. Great way to get started if you're not near a crossfit gym and all the olympic lifts looks a bit daunting.