To answer your question Indie I don't really do a lot of fun experiments I guess. My experience with chemistry has come from working at forensic and environmental labs (I majored in Biology). I do enjoy my work very much but what I do probably wouldn't "wow" anybody.
To get back on subject I did think of an experiment with acetic acid though. You can oxidize pennies with it in a solution of H202 (hydrogen peroxide) and acetic acid. If you let the solution sit there for awhile and evaporate you get blue copper acetate crystals. Or you can drop other metals in the solution such as Fe, Zn, or Pb and they will become plated with copper. So you can copper-plate a quarter if you wanted to. The reason this happens is because those metals are above Cu on the metal activity series, so the metals atoms will replace the Cu ions in the solution. For example for Iron:
Fe(s) + Cu(II)(aq) = Fe(II)(aq) + Cu(s)