I just want to add to the request for a fairly accurate RTC board, so that folks can build data logging applications with deeper sleep cycles for power saving, and use an an alarm interrupt from the RTC to wake. I know Tiny has an RTC in the works, but I would love to know eta, and the chip they are considering. The DS323x chips (rather than the cheaper DS1307s) have a built-in crystal and temperature compensation, which becomes more important in outdoor applications, and you can pull the internal temp data from the rtc, so you get that sensor for free.
And wrt stacking, somewhere in the forum there was a suggestion of a ribbon cable with stackable, mini connectors on both sides, which solves the problem of stacking multiple proto boards, and also deals with the battery holder on the RTC board (unless the rtc board had its own power connector, similar to the way they attach cmos batteries to the mother board in laptops)
