Regardless of whether they ever use them or not, cyclists certainly do like their multitools. The things can be heavy and bulky, though, which is why the Swiss-designed Daysaver was created – it combines nine tools in a single hex wrench.
At the base of the system is the actual wrench, made of corrosion-resistant high-tension chrome steel. Its two ends serve as 8-mm hex tools. Because those ends are hollow, though, two smaller-diameter, double-ended, interchangeable bits of other types can be inserted into them. Those two bits are in turn hollow on one end, allowing even skinnier bits to be nested within them.
Because the bits are held in place magnetically, they can simply be pulled out of the wrench and turned around to access the desired tool. Along with the 8-mm hex tools on the wrench itself, the interchangeable bits incorporate 2, 3, 4, 5 and 6-mm hex tools, a flat-blade screwdriver, a T25 torx tool, and a tool of the buyer's choice (which they stipulate upon ordering).
It should be noted that in order to keep the walls of the Daysaver sufficiently thick, system-specific bits are used. This means that if you lose one of the bits, you can't just buy another from the local hardware store.
The whole rig is 93 mm long by 43 mm wide (with bits protruding), and reportedly tips the scales at just 45 grams. It comes with plastic end caps, to keep its bits from poking holes in jersey pockets. That said, there's also an optional frame-mounted holder for the multitool, which is bolted onto the bike's existing water bottle cage bosses.
Should you be interested, the Daysaver is currently the subject of a Kickstarter campaign. Assuming it reaches production, a pledge of 70 Swiss francs (about US$75) will get you one.
Sources: Kickstarter, Daysaver