A toy drive organized in December by Cotter Union post office supervisor Allen LaPan collected more than 500 items for local children.     LaPan was impressed by students' generosity, but not surprised by it. "I had a student come in during finals week and hand me a sixty dollar check and say, `I don't have any toys, but please use this to buy some,' LaPan said. "This was not a student who can easily afford sixty dollars."     The toys were distributed during the holidays to needy families in central Maine.     Pam Tinto Pillay, assistant director of residential life, challenged hall staff to adopt area kids and families for the holidays, and every residence hall responded. "They did an amazing job," she said. Working with the Maine Children's Home and the Salvation Army, students provided holiday gifts and food for 18 individual children plus eight entire families.