Also, I get what you're saying, but I wanna help ICE! The content creator program is a great way for ICE to make some money and for fans/new publishers to get their feet wet. You can curate good content and see what chops potential publishers have before issuing a license (if you were so inclined...). Again, the buzz would be good. Having more adventures/settings using HARP would increase the appeal.
I'd suggest just go ahead and do it but be careful not to infringe ICE's copyrights and trademarks.
Copyrights are easy, just don't copy anything belonging to ICE. Trademarks are also easy - just put a prominent disclaimer on your title page that your work is unlicensed and unofficial, and explicitly acknowledge that the trademarks belong to ICE (and other respective owners, if any). BTW,
there's no such thing as "Intellectual Property".
If you wait for a license, you'll probably never get one - ICE and especially Nicholas seem far too busy at the moment to even evaluate new proposals, let alone take on more work (and evaluating stuff might
seem easy, but it can be very time-consuming work). Also, I'd personally rather ICE not get distracted from either Something Wicked or the Bestiary. That's totally selfish of me.
Without a content creator program, ICE won't directly benefit from royalties or licensing fees from your work but may benefit indirectly by increased sales. Increased sales of the rule books would be a far higher source of extra income than any royalties from some adventure modules.
You could even suggest that people who buy HARP books because of your work somehow let ICE know that your unofficial work helped drive some sales.
BTW, the low royalties for a small work in a tiny niche-market are one of the reasons I'm not personally interested in publishing anything for profit, I'd rather give it away under a CC-BY-SA license. A few cents or a few bucks per month would, to me, be far worse than getting nothing at all - there's no way it could ever make enough to even equal a minimum wage for the hours of writing and editing I put in, so it would turn a pleasant hobby activity into an unpleasant, unprofitable business venture or underpaid work. Also, this hobby was founded on actively DIY-ing stuff, rather than passive consumption. I've done a lot of free software development over the last few decades, and I don't see writing text as being any different from writing code, except that it's easier as there are far fewer syntax errors to debug :-)
PS: I just saw Nightblade's post - that's exactly the sort of thing I'm talking about.
IMO, other useful things to upload are conversion notes for existing adventures - but you have to be very careful not to copy anything directly from the original. Just include your conversion notes, ideas for how to handle things that are unusual for RM or HARP (or just different), stats for monsters, NPCs, races, traps, magic items, etc. I've done this for a few old BECMI modules (B11 mostly done - enough to play with at my table. B2, B12 & X1 partly) - the hardest part is reading through a module thoroughly and making a list of all monsters etc that need to be converted. BTW, most of the DCC modules already include such a list for each location and dungeon level. Also, you can't have large groups of any creature no matter how they are in other systems if you intend your players to fight them and survive. Unlike D&D, numbers really matter in RM & HARP, and a lowly kobold CAN take out a high-level tank fighter with a single lucky blow.
It's not hard to produce very nicely formatted documents in
markdown (which is trivially easy to learn - if you can write text, you can write markdown) that look very professional - similar to the common two-column adventure module format. Even
LaTeX isn't too hard to learn and is better if you have very complicated tables. There are templates for both that are designed for producing RPG content in familiar-looking styles, and both are frequently used in OSR and other DIY publishing and can be used to produce PDF, epub, html and other output formats from the same source files.
I'm not sure if I'd upload ONLY to the Vault here, though. It's great to have a central location for fan-made stuff but it just takes too long for any uploads to get approved. Probably better to also publish on your own blog or website, and post a link to it on the forum. Maybe get a stickied thread for such posts (announcements only, not for discussion)
There's some stuff like this in the Vault now, but almost all of it is over a decade old - very little has been added. I guess that maintaining the Vault here has only a very low priority for ICE staff.
Which is part of the reason why a DIY attitude is essential - don't add to the workload of ICE staff.