1. A computer-implemented method of visualizing a collection of graphs, each graph comprising an ordered set of pairs of values, each pair of values having a first value indicative of a quantity along a first axis and a second value indicative of a corresponding quantity along a second axis, said method comprising: providing a compressed display mode for each graph in which that graph is represented by a linear graph comprising a straight line along said first axis, said straight line having a visual property that varies along said first axis according to said second values, providing an expanded display mode for each graph in which that graph is represented by a two-dimensional graph aligned along said first axis with said linear graph, said two-dimensional graph being characterized by a magnification along said second axis; providing a compressed display in which all of said graphs are displayed in said compressed display mode, said straight lines corresponding to each graph being aligned with respect to one another and being presented in an ordered sequence; receiving input from a user identifying one of said linear graphs; and providing an expanded display in which said identified linear display is replaced by said two-dimensional graph corresponding to that identified linear graph, said two-dimensional graph and said linear graphs remaining in said ordered sequence relative to one another.