A few quick suggestions, without really looking thoroughly into the code:

• Saving any passwords in clear text is a Very Bad Idea™.
• Why are you limiting the max-length of the password?
• Do not set styles in JS, set classes instead and then style them with CSS.
• Use $this.hasClass("finished") instead of $this.attr("class") =="finished".
• You repeatedly access $this.attr("checked"), so it might be a good idea to store it in a var at the beginning of the change handler.