Beds:
- Monsters can awaken you during the night
- Moving your bedroom above or below ground level makes this less likely
- Beds work differently in SMP
- All players must go to bed for night to change to day
The Redstone Repeater is a block added to the game in Beta 1.3. It was originally implemented by Jeb[1][2]. It is designed to delay redstone signals, and right-clicking it will toggle the block through 4 possible settings; originally these settings were "1, 2, 5 and 7"[3], but this was changed to "1, 2, 3, and 4" for simplicity's sake[4]. Existing repeaters/delayers will still work[5]. They were designed to save space in Redstone Circuits.
As shown in the preview video[6] the block has three main functions: acting as a repeater, a diode, and a delayer. The block repeats signals it receives like a network bridge, so that using two not-gates every 15 blocks will no longer be necessary. Signals are also accepted only in some directions, allowing the block to function much like a diode in an electrical circuit. It also delays the signal so that long timing circuits of inverters will not be required for timed mechanisms any longer (though old timing grids will still work).
(Sources: http://www.minecraftwiki.net/wiki/Redstone_Repeater#As_Clock.2FDelay)
Isn't it to save space for Redstone Circuits then?