In case there weren't enough links below, let's start with this animation. In this video you can see a quick version of how aurora is created. At the beginning we see a solar flare and the rush of solar wind toward the earth. At the boundary of the earth's magnetic field the solar wind pushes on the sunward side of the earth's field and stretches out the tail on the anti-sunward side. As this stretching is occuring, the auroral oval is widening and moving southward. At some point, the system breaks, and the field lines snap back to a more dipole-like configuration, sending large amounts of plasma toward the earth along the field lines. All of this activity produces large currents flowing in various directions, and also causes the aurora. So the important things to look at when monitoring and predicting the space weather would be things like the sun, the solar wind, the shape of the earth's magnetic field, and the currents detected at earth.
Now we are ready to start stepping through these links.
First we have the Kp: General Activity Index. Kp is an auroral index, ranging from 0 to 9, that is derived from ground based magnetometers. Indices of 5 or higher indicated storm level geomagnetic activity. This plot is arranged by Carrington rotations, making it extremely useful. The sun rotates on an approximately 27 day schedule. So if there is some sort of coronal hole that we see on the sun, it will more than likely be back in view in 27 days. Since coronal holes, or solar flares, are responsible for increased geomagnetic activity, this is good information for long term predictions. If you look at this plot you can see how the days with increased Kp line up vertically.
Next is the condegram. This is a circular view of different parameters that also lines up the days in 27 day periods. You can choose from 8 different parameters, which is pretty spectacular. Kp index is one option, so you can look at that as well as the plot from the previous link, just to see how these two different views compare. The other choices you have are also quite interesting. Of particular note are the velocity of the solar wind and also the IMF Bz (zed component of the interplanetary magnetic field).
Now the links are for shorter range predictions. The various ACE pages show properties of the solar wind. ACE is a satellite that sits at a point of gravitational equilibrium between the earth and the sun, but is much closer to the earth (about 1.5 million km) than to the sun (about 148.5 million km). The delay time from when ACE sees something to when we see it is on the order of one hour, but varies with increases or decreases in the solar wind velocity.
NOAA's Today Website has a variety of things to check, including an image of the sun, and some of the parameters that you can see in the condegram like fluxes, but on a shorter time scale.
GOES Hp is one of my favorite plots to check, in case you were wondering. This plot is showing the one minute average of the parallel component of the magnetic field. The red line is from the geostationary satellite orbiting over the east coast, and the blue GOES is over Alaska, approximately. So if the Earth's magnetic field were a perfect dipole, the magnetic field would not vary as the satellite rotated from the sun side of the Earth to the anti-sunward side of the Earth. However, as discussed above, the field is slightly off from a dipole, and the more stretched out the tail is, the more likely we are to see aurora. On this plot the 'M' and 'N' mark midnight and noon respectively. If the parallel component of the field gets very low near midnight that is almost a sure sign that there will be aurora.
The final few pages we have are the GEDDS MSP and keograms which show optical data from Alaska, as well as magnetometer chains from Alaska and Canada which show ground magnetometer data from various sites.