There is actually a hints/solutions board, but it depends on how often you want to use it. If at all. But the tool is there if you're interested or at the point of giving up altogether.

http://forum.caravelgames.com/userfile.php?f=/11/71/0&BoardID=1#611/3715/0/0

Thanks, even if the room images are all black for me O_o

Me too...you'll still get the map above though, you just won't be able to see the room. From there click on the room on the map or navigate it using the buttons in the room section then check hints.

Have used this a few times to find secret rooms. Think there is a hidden room in 4N? Click to 4N, hit search and see if anyone has asked for help. Then off to 3N to try and find the crumbly wall or path in I didn't notice the first time I was there.

Although I will say this won't always work since the path to a secret room will sometimes take place a few rooms away (some of the entrances are fairly devious)...but it at least gives you an idea of where to start.

Starmaker found a list about total rooms for each level in Drod1: is there something similar for the sequels? (with a separated secret rooms count maybe?)

Some of the other (many!) holds have those images, though.

I did, then I got addicted to math. I haven't played anything in two weeks, but when I think about what to play when I have more free time, it's "which hold*", not "which game".
*Odd Jobs Expert, probably. Diving level is best level.

I made it. I can make one for JtRH, too.

edit:
1 23/28
2 14/15
3 14/14
4 14/16
5 9/10
6 16/18
7 11/11
8 19/20
9 11/13
10 8/11
11 17/19
12 10/11
13 21/22
14 16/18
15 12/13
16 19/21 (2S2E is THE WORST)
17 10/11
18 12/13
19 19/20
20 10/11
21 13/14
22 13/16
23 18/18
24 14/16
25 23/23
bonus: 72 (only a handful are puzzles, though)

Ah ok, thanks! (woa, lots of secret rooms)
Btw, I completed your Drod1 list with the secrets too, if anyone needs them.