heating the weed can make it stronger by reactions of decarboxylation and isomerization, where some inactive cannabinoids (THCA and CBD) are transformed in THC.
doing this heating in microwave is a controversial matter. there were many posts about this. some claim it works, some claim it dont. i say it works. microwave the weed some 2-3 minutes and then smoke it. the effects will be more sativa-like (mind high) than that from un-microwaved weed.

the effects of heating the weed are discussed in the threads below:

http://boards.cannabis.com/recreatio...-question.html

http://boards.cannabis.com/experienc...otency-mj.html