1. In a game where damage is rolled separately, have the players roll for damage simultaneously with their hit roll. This is especially pertinent to d20/D&D-style dungeon crawl games. You'd be surprised how much quicker this can make combat, rather than having a second roll for when you hit.
2. Do all the rolling yourself. It's a mighty challenge, but if you're up to it, just take the dice away from the players and do the rolling yourself, then narrate the results. I've had a lot of pushback on this over the years, but usually all it takes is one good combat encounter where I'm narrating each and every sword-swing before the players are completely cool with it. This is an especially good idea with RPGs built around a single roll, like Call of Cthulhu (this also allows investigators to conveniently "succeed" at rolls to find those essential clues!)
3. Roll the dice a bunch of times by yourself and write down the results. Again, this works best with one-roll engines like Call of Cthulhu or True 20. Basically, you roll the die a few dozen times, write down the numbers, and then when you need to roll against a player's perception to notice an ambush or something, mark the first number on the list off and use that as the roll. As with tip 1, above, you'd be surprised how many seconds this saves you over the course of the session...seconds which can be better spent on describing the game and letting the story flow.
4. Use text messages for in-game messages. This is great because it hides important game information as a simple, run-of-the-mill text message. It avoids "love letter" syndrome where the players know that something is going on. Oh, Jim is fine, he's just texting his wife, he didn't just get a text from the GM saying that the infection from the zombie bite is spreading...
5. Use one-on-one conferences. This is related to 4, above. If you want to spotlight a particular character ahead of time, take that player aside and talk to him or her about it. This is different than a simple message because you can actually talk to the player, give and take feedback, and set up something spectacular for later. This leads into...
6. Do something special in every adventure. If you've read or played 13th Age, you know that characters in that game are made with "one unique thing," one special, non-mechanical trait that is exclusive to that character. Do the same thing with your adventures. Include one crazy little detail or sequence and swear to never do that again in another adventure (or, at least, not in the same campaign). Maybe one of the players is hit with a spell that mutes his character, and he has to communicate vital information in real-life with charades. Maybe you have a fight scene underwater. Maybe you play an important scene in real-time. Whatever you do, it helps to not only break up the monotony of doing the same thing over and over, but it adds individuality to an adventure and makes the session that much more memorable.
7. Ask your players how you can be a better GM. This one I take quite seriously. Do not let your players get away with "I didn't see anything wrong at all. I had a great time!" That may be true, that the players had a great time. But you did do something wrong. Maybe it was minor. Maybe it was absolutely trivial. That's fine. But there had to have been something that didn't play out as fun as it sounded on paper, or some detail that didn't work, or something. It could even be a logistical detail, like the room was too hot or you didn't take enough breaks. Never settle for "good game." Always be trying to be better. That doesn't mean you can't be proud of yourself, or that you shouldn't enjoy the work you've done...it just means you should always have a couple of ideas for how to improve your game on hand for the next time you come to the table.
I actually have more tips I could give, but I'm going to stop there for now. As with part one, I intend to revisit this blog entry frequently and update it with new tips, both that I think of on my own, and anything anyone shares with me in the community. Thanks for reading!