Here are two quick tips:
1. Managing closed web parts
A customer emailed me in a panic… He closed a web part and thought he lost the entire content. :). Here is a nice article by Mark Miller that explains how to solve this problem.
2. Filtering calendar
If you want to filter events in a calendar list by Start Time (End Time) you want be able to do so. The problem is SharePoint does not allow you to use Start Time (EndTime) columns as filters. However here is a nice workaround to solve that problem.