I'm going to be honest. Axle's aren't something that crosses my mind all the time. They are more of a set and forget, maybe check every couple of rides to make sure they are still tight.
But when I came across The Robert Axle Project it changed my mind. They solved a couple points that I didn't even think that I needed to have fixed. First thing that you notice is that they are considerably lighter than stock axles.
They get the weight down by using 7075 aluminum, machining it down to diameter, then boring out the inside of the axle as well. All done while keeping tolerances as tight as possible. This gets the front axle down to 53gr for a 15x110mm. I don't have a scale to measure grams, but you can notice the difference between the two. Rear axle comes in at 45gr, about 40% less than stock.
A good portion of the weight loss comes from removing the quick release handle. The Robert Axle Project favours using a 6mm hex instead of handles, giving the axle's a narrower width and thus greater clearance. I would say that is a win, win.
Price: Front $44 usd, Rear $48 usd.