Linux services: is there a GUI for services?

Try sysv-rc-conf to alter the runlevel settings.

and chkconfig to see what's running

Don't forget that ubuntu (and others?) are starting to use the Upstart Startup Manager, so you'll have to keep an eye on the /etc/init directory too

Old thread, but yes now there is! Check out the systemd-manager

Systemd Manager

This application is a systemd service manager written in the Rust programming language with GTK3 as the graphical user interface of choice. The units are filtered into three separate lists: services, sockets, and timers. As a unit is selected in the left pane, the right pane is updated with information pertaining to that unit, and the right headerbar is updated to reflect the status of the unit where you may disable/enable and start/stop the selected unit. Services are units that are activated immediately, sockets are units that are activated when they are needed, and timers are units that activate on a regular time interval. In addition to display units, the application also provides stats generated by systemd-analyze on the Systemd Analyze view.

On my Redhat (err, Centos) box:

curses: ntsysv

gui: system-config-services

On another note, remember to add the descriptive comment stanza to the top of your file. chkconfig and other tools (like ntsysv) read this.