Many Meforshim who comment on this week's Parsha ask the age old question of why the tower of Bavel was built, and there are many suggested answers. One of the simplest answers is that it was built as a place to climb to safety, in case of another flood.
However, there is a Gemara in Sanhedrin (דף קח) which suggests that the people of Bavel felt it was "unfair" that Hashem alone controlled the heavens. They felt that Hashem was limiting their domination of the world. They therefore planned to set up a huge idol at the top of the tower with a sword in its hand, as a symbol of a declaration of war against Hashem.
Many Meforshim hold that the people of Bavel were very scientifically advanced. According to Rabbeinu Bachya, the tower was meant to serve as a technological instrument (a lightning rod) to prevent fire, (or lightning as we know it) from striking the earth. This was done as a precautionary measure, since many people feared that Hashem might next bring about the destruction of the world through fire, instead of another flood.
Rav Yehonasan Eibeschutz explains in his sefer "Tiferes Yehonasan" that the tower was a place from which the people of Bavel would be able to launch weapons, such as missiles. Rav Eibeschutz even goes as far as to say the tower was to become like a launching pad so that the people could eventually settle on the moon, where they would find refuge from the natural calamities of this world. Rabbeinu Bachya also suggests that the people of Bavel planned on going to Heaven, where they thought that they could escape death, and live forever.
The Ha'amek Davar writes that the tower was to serve as a watchtower, where people could be watched and guarded as a flock is watched by its shepherd. Other Meforshim feel that the people of Bavel denied Hashem's role in bringing the flood, and suggested that it was simply a natural phenomenon. They figured that every 1,656 years (the amount of years between the Creation and the flood), the heavens shake, and cause a flood. In order to prevent the heavens from collapsing again, they wanted to build supporting beams for the heavens, and that was the purpose of the tower. All of these interpretations point to man's failure to understand his role in the world as opposed to the role of Hashem, something we still ought to think about.