This is a great website (http://wg7j.reinalda.net/gridmapper/gridmapper.php) that enables you to display the 6m grid squares that you have worked. Actually you can display for any band, mode etc but I use it to show the 6m squares as think it’s really interesting to see where the Es cloud have formed.

Below is a picture of all the 6m squares I have worked (224) since being licensed (click to see large picture). A red square means the QSO is unconfirmed in LOTW whilst green is confirmed.