A few days ago I decided to add Jpan's hack to mine. I stupidly downloaded v1.0 and tried applying it to an original Fire Red rom, then applied Operation Digipedia. Obviously it crashed the game. Then I realized there was a v1.1 of his hack. Thank Christ because I really wanted his patch included with my hack.
The v1.1 has an application that let's you apply each individual section of the hack, which is just awesome. So we have the Jpan patch under our wing. So what does this patch do and why did I want it so bad?
Jpan's patch extends what you can do with the rom. In your usual hack you only have 100-and-some-odd OverWorld characters that you can edit. A lot of them use the same palette, so one change in the palette means a change in all the Overworlds that use the palette. The patch extends this list to up to 256 more OverWorlds, each with their own palette.
There are a lot more features that are added/extended in his patch, but I haven't got around to looking at them all yet. This will make a major improvement on the hack in the long run, but for now I just wanted it for the OverWorlds.
The next hack I would like to include is Jambo51's patch. It increases the amount of available Pokemon to 659, adds more evolution stones, adds forms, and fixes the National Dex glitch. He hasn't fully released it yet though. I think it's on Alpha3 at the moment. He's worked with Jpan a lot on this patch too so hopefully they'll do the same thing with this as they did with Jpan's patch with the easy to apply application.