When your plugin updates, it attempts to create a directory "visitor-maps-backup" in "wp-content" to save a copy of the "GeoLiteCity.dat" file. That's great, because it's a 28 meg file, and it would be a PITA to have to upload it every time the plugin updates.
The problem is that it doesn't work for me because i don't want to make my "wp_content" directory writable for plugins (just in case). It would be handy if it were possible to set where the temporary directory could be created - for example, i could use "wp-content/uploads".
Another suggestion is based on a localization problem i ran into. The "vmfont.ttf" that comes with the plugin does not include Esperanto characters like ĝ and ŭ, so i substitute my own "vmfont.ttf". Unfortunately, every time the plugin updates, that gets replaced with the original version. It would be nice if it were possible to ask that the font be copied as well as the database file during updates.
By extension, all of the flag and map graphics would be nice to keep, in the event that someone has made their own custom graphic sets.