anything on the sativa side of things, like say a haze, or kali mist, or a land race, is the happy, up, motivational weed, often paranoid as well comes with a heavy sativa.
indicas are pretty much the opposite end of the spectrum, they are good for pain, are more couch lock, don't move all day type of smoke.. some nice heavy indicas are umm, let's see, afghani, deep chunk, bubba kush, and many many others..
something new on the scene are high cbd strains, which are supposed to work great for pain, and not get the user as high as a strain with a higher thc and lower cbd strain would do.. a few breeders are working with cbd strains atm, bodhi is giving high cbd seeds away with a purchase of his other strains i have recently read some where.. there's also the cbd crew, and strains like harlequen(Sp?), and cannatonic and ac/dc and a few others as well..