If you're looking for anime similar to Infinite Stratos, you might like these titles. All recommendations are made by Anime-Planet users like you!
When deadly asteroids threaten Earth, an elite team of interceptors--the Meteor Sweepers--are formed. Now, rookie pilot Honjou Mikaze and her three friends are caught up in tumultuous events that may expose a sinister conspiracy and put the fate of the world into the hands of a few young girls...
Teenage girls, high tech weapons, save the world... Both of these anime have a lot in common. Stratos 4 has a little more realistic premise (aliens notwithstanding), shoot down meteor fragments to save the world.
Infinite stratos is a bit more science fictiony, with personal mechs, and what might as well be magic. Both start off fairly similar. Protaganists going to school, learning to operate the high tech equipment, deal with personal stuff, things like that.
IS is a little different in that there is a romance/harem thread to go along with it, Stratos 4 lacks both the Harem completely, and no real romance to speak of.
While different, if you like to see Teenage Girls (and a guy in IS) fly planes and mechs and save the world, if you like one, I highly recommend checking out the other.
Both these shows are fanservice vehicles for their cast of well endowed females. Both shows involve the girls all fighting, but Infinite Stratos uses mechs to fight.
Freezing is more explicit with actual nudity. If you're looking for some ecchi fanservice with minimal plot then these are the shows for you.
Sousuke Sagara is far from the average high school student - not only is he highly trained in military tactics, he puts his knowledge to use in every single applicable situation (and even those nonapplicable ones.) So, when confronted with high school, he tends to turn average high school experiences into off-the-wall adventures. Love letters become terrorist threats and field trips become commando operations; his survival depends on the watchful eye of his best friend and classmate, Kaname. Together, they may just make it out of high school alive...