We might have the brightest comet ever to look at:
The potential comet is a dwarf planet in the Kuiper belt, designated 2003 EL61. Astronomers at Caltech have plotted its likely path, and have found that a close encounter with Neptune could disturb its path enough to send it tumbling into the inner solar system, where it would become a short period comet.
Alternatively, the encounter with Neptune could slingshot the planetoid away from the sun, into the Oort cloud, or even out of the solar system altogether.
Only one thing though, you'll have to wait a long time. 2 million years or so shoud do it.