What web server are you currently using? Apache, Nginx, lighttpd, Cherokee, IIS, Custom, Other? Are you happy with your current setup or do you plan on switching to a different web server for your next project?
For most of my career I have used Apache. Just recently I choose to run Nginx for a new project and I cant see myself going back to Apache. Just today I came across the Cherokee web server and that looked pretty slick. Does anyone have any experience with Cherokee?
At work: custom web server hiding behind a lighttpd reverse proxy. I'm not entirely happy with either part of this, although it's more the fault of the back end and all its legacy c++ issues. I'd consider switching to nginx on the front end if I could be sure it wasn't going to interfere with our e-mail setup.
Personal server: thttpd. It could log cgi scripts better. Otherwise I'm happy with it.
Laptops: thttpd, sending all requests for localhost to a cgi script. If I could persuade it to log cgi errors, it would be perfect.
For personal projects I use Apache, not because of its performance characteristics, but because it's the most common and thus when I want to do something crazy I am most likely to find that someone else who uses it has already written up an explanation of how to do it. For development I also use the Django default/debug webserver a lot.
For work I use GWS but I suspect that is not helpful to you ;-)