I would recomend that anything you find that aids you as a DM/GM, be sure to make use of it. For myself, the main tool that I use as a DM/GM is my computer. I prefer to have all the major events typed up and printed out (I have a pc as opposed to a laptop). This allows me to have all the information inside a binder, right in front of me. This way when it says that a creature has 6+6 Hit Dice, I have already previously rolled this and have the number ready. This holds true for any bit of information on people, places, or things in the game. Of course, the computer also gives me access to sites such as P&PG to be able to find players, get ideas from fellow DM/GMs, and a place to keep my campaign log.
I have never used a name, place, or plot generator. As for DM Secretary, I must admit that I do not recall seeing it mentioned since before this question. As for a dice roller, until Farcaster added it to the Chat feature on here, I had never used one. I have used the one on the Chat feature. It does come in quite handy. Myself and a few other members did a small impromptu D&D game using primarily 2E rules. Having the dice roller meant that none of us had to have a bunch of dice on the table along with the computer to roll
Now some may say that this doesn't qualify, or isn't what what meant by the question, but I feel that it does. One of the best tools that a DM/GM can use is the other members of the group. Be sure to make use of the knowledge that your players have. You may have one person that is so into making characters that they will know most if not all of the bonuses and flaws of a particular class or race. Another person may be really good with spells. What ever a certain persons forte is, be sure to use it to your advantage. Anything that can keep from having to completely stop and research something is always a big plus for gaming.