I know magnetic monopoles do not exist, but out of curiousity what could we do with one if we ever found one?

 

magnetic shielding is one possibility.

Getting a good grip on high temp plasma is another. (Fusion is AWESOME)

The Hydrogen fusion 'Ramjet' design engine (as theorized by Larry Niven) for largeC% space flight.

 

Examples of monopoles have been discovered, though they may not be exactly as you think they should be. Search "monopoles" on this site (or google).

 

I think we could make one, if we could get a ball of pure positrons or a ball of pure electrons.
Of course, it would require extreme amounts of energy to contain it.
maybe a fullerene complex containing large amounts of charged particled?

 

Like I said, they have been discovered, their structure isn't anything like you'd imagine. It is worth the search.

 

Like I said, they have been discovered, their structure isn't anything like you'd imagine. It is worth the search.

It's definitely worth the search. However, it's important to point out that the magnetic monopoles that have been discovered are better referred to as psuedo-monopoles (at least, in my opinion). They are entities analogous to electron-holes in a semiconductor, which are not real fundamental particles. The psuedo-monopoles have the various important properties of monopoles in special solid state materials, just like holes in a semiconductor have particle properties. But, they are not really the fundamental monopoles that physicists search for like so many "holy-grails".

The discovery of real monopoles would have a major impact on much of theoretical physics, while the discovery of psuedo-monopoles has been very interesting experimental physics and ultimately may result in very useful technology in the future.