This could be a borderline advertisement, not to mention subjective, but the question is an honest one. For the last two months, I\'ve been developing a new open source profiler
Download the Team Suite version of Visual Studio 2010 Beta 1 (free for 6 months or so?), and profile a C# application.
Trust me. :)
Edit: Line-by-line mode helped me isolate an operator that was causing a performance problem. I could have found it without per-line highlighting, but when you can scroll around and see the hot lines using it you can fix it soooo easily.
Oh, and if you want feedback/help, contact me separately.
Summary View: select any section of the CPU chart to filter.
(source: 280z28.org)
I love the line-by-line in the margin:
(source: 280z28.org)