There are so many variations on the original and good old useful version of Linux top that I figured I would list a few of the ones that I find handy on occasion. As with anything else, they all have their usefulness and each one can be more useful than any other at a particular time. You will need to figure out for yourself what is the most useful for what you are trying to accomplish.
I have used all of these at one time or another. They fall into the following general categories: general, network/service, and daemon. I am sure that are plenty more than I have listed here (in fact I know there are since I didn’t include any X based programs). If there is one that you find useful, please let me know about it as I always like to learn more about whats out there.
Atop is an ASCII full-screen performance monitor that is capable of reporting the activity of all processes (even if processes have finished during the interval), daily logging of system and process activity for long-term analysis, highlighting overloaded system resources by using colors, etc. At regular intervals, it shows system-level activity related to the CPU, memory, swap, disks, and network layers, and for every active process it shows the CPU utilization, the memory growth, priority, username, state, and exit code.
This is htop, an interactive process viewer for Linux. It is a text-mode application (for console or X terminals) and requires ncurses.
iftop does for network usage what top(1) does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts.
Jnettop allows administrators of routers to watch online traffic coming across the network in a fashion similar to the way top displays statistics about processes.
This program has a top like display which shows the different packet types. Possibly useful to determine the nature of packets on a given network and how much bandwidth they are using.
ntop is a network traffic probe that shows the network usage, similar to what the popular top Unix command does. ntop is based on libpcap and it has been written in a portable way in order to virtually run on every Unix platform and on Win32 as well.
dnstop is a libpcap application (ala tcpdump) that displays various tables of DNS traffic on your network.
Pftop is a small, curses-based utility for real-time display of active states and rule statistics for pf, the packet filter. for OpenBSD.
Network tool for monitoring IPv4 activity. Iptraf, tcpdump, trafshow have not such ability. Gives sorted traffic load speed on each IP. Helps detect the channel overload and maybe sources of attacks. Requeres ULOG target of iptables.
mtop (MySQL top) monitors a MySQL server showing the queries which are taking the most amount of time to complete.
mytop is a console-based (non-gui) tool for monitoring the threads and overall performance of a MySQL 3.22.x, 3.23.x, and 4.x server.
innotop is a ‘top’ clone for MySQL with more features and flexibility than similar tools.
display PostgreSQL performance info like `top’
Apachetop is a curses-based top-like display for Apache information, including requests per second, bytes per second, most popular URLs, etc.
This is a part of the ISIS (Integrated Samba Inspection Service) Java framework. I have never tried this myself, but it would be great to see a top of what is currently being done by Samba on a machine.