One of my top improvement recommendations is to play correspondence chess because of the possibilities it offers to do some opening research during the games (providing this is allowed by the tournament rules). Correspondence servers such as the Free Internet Chess and Go Server offer an excellent interface for such games.
Many players prefer to stay relatively true to the original form of correspondence chess by sending moves by email. I can see the point behind this as it has a more social dimension than playing anonymous moves on a server. This provides the opportunity to make new friends whilst getting rid of some of the unsportsmanlike behaviour (eg losing on time rather than resigning) that is common to servers. Mark McCready recently showed me a good site for this, the International Email Chess Club.
Of course things can still go horribly wrong as chess players tend to be an eccentric bunch at the best of times. And this hilarious parody by Woody Allen contains more than a little truth.