GRUB2 is the next version of popular boot loader, have a lot of features.
Read about on http://www.gnu.org/software/grub/manual/grub.html
Here simple steps to install:
1. Download sources, for ex. for Slackware use http://slackbuilds.org/repository/13.37/system/grub2/grub-1.99.tar.xz
2. Install & config:
./configure make install clean parted /dev/sda set 1 bios_grub on grub-install --no-floppy /dev/sda grub-mkconfig -o /boot/grub/grub.cfg
If your partition table is GPT, use parted /dev/sda set 1 bios_grub on to install grub.