Harmony Hollow software has some great software and a really great set for teachers.
The Totally Free Teacher's Tool Suite is a set of free software items that are very useful for teachers. The suite includes Gift Wiz, The Hat, Cool Timer, and Text Tally.
Gift Wiz is a tool to select and match up people for gift exchanges, but I have used it to match up partners for labs and projects.
The Hat allows you to randomize any list. I use it to randomly pick on students or to sort students in different orders.
Cool Timer is an on screen timer. I project it up on the board so that students can see how much time they have left for the activity they are working on. You can select different sounds to use as the alert. I have fun picking different ones.
Text Tally is an easy way to count words, characters, and lines in a document.
I use the first three quite often, as do a lot of my colleagues. One word of caution, our school's blocking software doesn't allow us to get to Harmony Hollow's site so you might need to download the program and home and then bring it in to school.