I was thinking about this kind of thing the other day. I mean, as a DM the thing I need the most is more time! So, it got me to thinking that what I needed were tools that I could use to reduce the amount of time it took me to write my game.
I think there is a fine-line between offering up lots of handy information, and not offering up so much that DMs get lost in all the stuff, they don't know where to turn.
I'm still waiting for the "big book of ideas", but it's been 3 years now, and I still haven't seen that one. I may have to just write that one myself, I suppose.
Magic items. That's another book that I considered doing - a big book of fully fleshed out, unique magic items. That would save me lots of time.
Maps. I can always use good, unmarked, interesting maps of a multitude of various locations. I do not need maps of Inns, or castles, or brothels, or anything like that. That stuff I can just make up. I need maps of dungeons, and caves, and sewer complexes. Big maps, small maps, everything in between. It's even better if it's drawn in three dimensions.
If I had all that stuff, I'd be all set.
One more thing, I will pay cash money for a random memorized spell lists for all kinds of characters at every level.
So, like make a bard at 1st level, and write down what his spells are. And the same bard at level 2, all the way up to 20. And provide a theme - "This bard specializes in clerical magic, and defensive spells", or "this bard focuses on illusionary spells". Clerics (of various gods, and alignments..), sorcerers - you could get creative here, with so many ways to specialize, like "ice" sorcerers, or enchantment sorcerers, or "fire" sorcerers, or any number of combinations; rangers, paladins, druids, you get the idea. I could have used that last game when I needed the spell list of a couple of mummy priests. I decided at the last minute that I would make them priests, and so I just had to kind of guess what their spell list might look like. I pulled it off.... ok..., but if I had this little puppy, I'd been all set. CMG Mark, this sounds like something right up your alley. Get cracking on this!
And while I'm thinking about it - for those publishers that put out books on templates, if you could go ahead and build a website so that I can take any MM monster, and slap on any number of templates, and get the stats for that creature, that'd be great. Yea.. *in my best Office Space voice*
So many good ideas here. I should just shut up and go write these so I can get rich!*
*as if.