Via John Robbins, I came across this little gem today. It's a registry setting that lets you display vertical guidelines in Visual Studio (2002, 2003, or 2005). This is handy as a cue that you might be writing lines that will be too long for your teammates to read without scrolling. Looks a bit like this:
Here's a .reg file for doing it in VS.NET 2003. Note that I've set my guides in columns 80 and 120 - you'll probably want something different.
Windows Registry Editor Version 5.00
"Guides"="RGB(128,0,0) 80, 120"