Hi everyone. I thought that I would drop a program that I wrote into here. There are likely better tunneling programs out there, but this one works very effectively for what I use it for. For the best results, use two turtles working in tandem.

http://pastebin.com/7FMwz5Lv

Here are the details and usage (pardon the alignment on the diagrams; spaces do not appear to be handled correctly in the code snippets):


-- baleTunnel(length, refuel, torches, unload, tunnels, gap, verbose)
--
-- Example:
-- baleTunnel 36 true true true 3 2 true
-- baleTunnel digs a 3 wide, 3 high tunnel in the length specified.
-- With default settings, fuel expenditure is 144.  5 for each block and 1 for the return trip.
-- arguments:
-- length  - int  - the length of the tunnel (default 24)
-- refuel  - bool - the turtle will always refuel if necessary regardless of this setting (fuel should go
--				  into slot 1, but if there is no fuel in slot 1, he will check all slots) but this is
--				  required for unloading options(default false).  If you don't want him to use fuel, -- --				  don't leave fuel in him.
-- torches - bool - the turtle will place a torch on the ground every 6 blocks (torches go in slot 16),
--				  alternating left and right (default false)
-- unload  - bool - if you place a chest at EACH tunnel origin, the turtle will unload  (default false)
-- tunnels - int  - the number of tunnels to mine - a two block gap is placed between each tunnel
--				  (default 1)
-- gap	 - int  - the number of blocks in between the tunnels  (default 2)
-- verbose - bool - if you trust your arguments or have written a batch, bypass the confirmation
--				  (default true)
-- ---
-- Knowledge of the turtle pattern is necessary in order to properly place chests.  See below, using default gap of 2.
-- ---
-- OOOOOOOOOOOOOOO
--   C    C    C
--   T    t    t
-- OXXXOOXXXOOXXXO
-- OXXXOOXXXOOXXXO
-- OXXXOOXXXOOXXXO
-- ---
-- O - Unmined block
-- C - Chest
-- T - Turtle starting point
-- t - Turtle starting points of subsequent tunnels beyond the first
-- X - Desgnated for mining
-- ---
-- The concept behind this is to have the turtle do the lion's share of mining and to manually spot
-- check the unmined blocks that are remaining.  A very effective method is to work in tandem with two
-- turtles in the following manner:
--
-- OXXXOOXXXOOXXXO
-- OXXXOOXXXOOXXXO
-- OXXXOOXXXOOXXXO
--   t    t    T
--   C    C    C
--   T    t    t
-- OXXXOOXXXOOXXXO
-- OXXXOOXXXOOXXXO
-- OXXXOOXXXOOXXXO
-- ---
-- Two directions are mined at the same time while you mine along with them, cleaning the floors,
-- ceilings, and walls in between.