One distro that's certainly worth a try regardless, is, Arch Linux
- Similar to what P@ckman's saying - although it doesn't rival Gentoo in this area (packages), it does provide a smooth, lean environment for putting your distro together from "scratch" - go for an FTP installation and only install the base
packages - then on reboot etc, you can start adding to with:
# pacman -Sy <package>
and so on, and so on...... to build your system up as you require - a straightforward way to create a lean system without the time-issue ala Gentoo.