The French term 'à la mode' means "of the fashion' (i.e., what is in fashion). It is also used to describe a dessert served with ice cream. So if you serve crêpes with ice cream, it is 'crêpes à la mode' .
In general ice cream (particularly vanilla ice cream) goes one with dessert crêpes, but of course one would not serve it with a non-sweet crêpe (e.g. one with a cheese or meat filling).
One of the most popular recipes for children (and adults) is Crêpes Suzette served with vanilla ice cream, which then becomes 'Crêpes Suzette à la Mode'. Of course, Crêpes Suzette is not served with ice cream in the traditional recipe. However, kids really like it, so why not?
For related recipes and information, click on Crêpes Recipes.