I have two ratchets in my tool kit that are sufficiently useful that I think everyone should know about them.
The first is this little (3" OAL) fellow...
One side has a fitting to accept standard 1/4" sockets while the other side has a hex socket to accept the ubiquitous standard 1/4" hex driver bits. Its size makes it perfect for getting into tight places. With a socket on one side and a screwdriver bit on the other, changing from one to the other during a job is just a matter of flipping the wrench over.
Continuing with the one wrench for two different jobs theme, this Harbor Freight wrench...
has a 1/4" ratchet on one end and a 3/8" ratchet on the other end. It's stored in my toolbox with a 1/4 to 3/8 adaptor on the 1/4" end and a 3/8 to 1/4 adaptor on the 3/8 end. This arrangement allows me to quickly configure the wrench as two 1/4 sockets, two 3/8 sockets or, obviously, one 1/4 and one 3/8. With a bag of socket-drive hex and screwdriver bits, you're ready for just about any fastener that comes along.