I always thought of Venus as one of the most useless planets in our solar system. Too hot. Can't land there and do anything useful. But the atmosphere has alot of CO2 if we found a way to utilize it.

Venusian Air Plants:

Like terrestrial kelp, which float on the open ocean using sacs filled with air, Venusian Air Plants would grow sacs filled with hydrogen to float in the upper atmosphere. It would absorb CO2 and H2SO4 from the atmosphere, use the CO2 to grow and maintain itself via photosynthesis, and bacteria in the sacs would use the H2SO4 to hydrolyze some of it's host's cellulosic matter into glucose for nourishment and release excess methane for system buoyancy.

I just made this up, so I'm not at all sure about the chemistry. Herbivores use bacteria to break down plant fiber, so symbiotic relationships involving bacteria are common, with this variation perhaps plausible. Alot of sci-fi stories out there involve plants growing in space, in total vacuum, even so large as to encircle a star. Don't ask me what they use for building material.