I'd have to say my best investment last year was the Lowrance X67C ice machine. Like fishdawg I use it all year round, as a portable on the hardwater, convert to bow mount for summer and then a portable again for the annual flyin. Great little unit for the dollar and the colour screen makes reading the structure so much easier.
Also outifitted my boat this year with a mast and planer boards along with two cannon downriggers( Thanks KyleM ). Both great set ups, now if I could just find the time to get out and fish more.
I guess no bad investments this summer.
Oh yeah I also bought a 2 dollar lottery ticket that paid off. Thanks to Muskies Canada and Richard of Ottawa River Trophy Muskie Charters for a great trip, 2 days of fun times fishing and learning from the guide and my fishing partner. You can't really put a price on that but a great investment.
Mike