I go brush my teeth right after supper. This helps signal me that my eating is done for the day.
I also chew a lot of gum in the evenings.
When the weather is decent I go for walks in the evenings, just like Ferumbras. It helps.
Handicrafts such as knitting or crocheting, that sort of activity, helps keep my hands out of the cookie jar.
I don't think there is any one easy answer to the problem of evening snacking. We just gotta keep trying.