here is a little experiment for you....
1) get 30 or more people to each use one of those 12 inch by 12 inch mirror tiles to reflect the sunlight on a very sunny day as a spot onto an object, e.g. the alarm bell box on your house.
2) stand in facination as the object melts !
experiment 2
1) get a magnifying glass
2) on a very sunny day focus the rays of the sun onto the smallest area you can on the back of your hand.
3) see if you can last for 10 seconds before the agonising pain of your skin burning becomes unbearable.
only joking....
DO NOT TRY EITHER OF THESE AS THEY ARE BOTH STUPID AND VERY DANGEROUS. You need to bear in mind that the sun is one powerful beast.
As for your suggestions...
The power of the sun has already been utilised for solar furnaces. Here a number of mirrors reflect the rays on the sun onto a single point. The temperature generated is enough to melt steel.
With regards to the lighting application you mention is concerned, this also has been done. For this a solar cell array will be used to power the detector circuitry and motor mechanism needed to move a mirror to the position for optimal light transfer. This is then transfered along conduits (with mirrors to allow beams to travel arround corners) until it gets to the room where light is needed.
On a lighter finishing note, I have also seen advertised an automatic plant turner that uses a solar cell to drive a motor that rotates a plant pot ensuring even sun all round.