I rewrote Spell Law for my own RM campaign over the last few years and recently updated it with some changes coming through RMU--specifically Size Rules, Fatigue Rules, Breakage Rules. However it's probably best suited for the older versions of RM and easily adapted if some of the rules don't fit your game style. It includes:
1. Alternative rules for SCR's and spell acquisition.
2. Spell lists are grouped by similarity and not by profession (but includes a chart to assign these new lists to current, companion and RMU professions).
3. Expanded lists: 60 Essence lists, 54 Channeling and 45 Mentalism, plus another 30 lists for alchemy(investiture), written magic(runes, symbols, glyphs, signs, sigils), performance magic(songs, tales, music, dance and art).
4. Consolidated spells that eliminate redundancy and filler spells. I added a lot of new spells--around 4000 total spells.
5. Created greater power/ability distinctions between the different realms.
6. Includes over 50 "cantrips"
7. New rules governing magic items.
For now I'm going to leave out most of the alternate rules and just start posting up spell lists starting with the realm of Essence....