WW Vulpeculae is a young stellar variable of the UXOR or UX Orionis class. These stars are known to undergo sudden, random, and very dramatic drops in brightness of up to several magnitudes. It's believed that the fades in the UXORs are caused by obscuration by some mechanism -- either a clumpy accretion disk or infalling matter in the form of cometary bodies.
The UXORs, like many of the other variable YSOs, reward patient watching with occasionally spectacular displays. Visual monitoring of the light curves isn't likely to yield a lot of new information for well-established sources; instrumental photometry that accurately measures both the change in light along with changes in spectrum (by measuring the light in two or more filters) can tell you more about why the star is changing over time. However, for pure "fun", the YSOs, and UXORs in particular can be a treat for every observer. And they're also a great way to observe how active variable stars can be. For more information on Young Stellar Object observing (both visual and CCD) visit the YSO Section website.