Note 1: Don't tell me about content that is obviously planned but not yet complete (unless it has been incomplete for a LONG time) ... e.g. http://wiki.feed-the-beast.com/index.php?title=Category:Soul_Shards
Please don't slate me for this, as I can't tell if the intention is there to put more information - but the Gregtech page *only* currently lists a number of machines from IC2 that are changed if Gregtech is installed. I'd like to see which machines it adds, the fact that some recipes (eg cells) are also changed, more detailed information on the configs, and a few general guides, such as "what you need before you can make a solar panel". It's such a contentious mod, yet there's very little information in the FTB wiki about it. Information on the bigger machines, like the industrial furnace, would be really useful also, as NEI doesn't stipulate anything about multi-block structures. We're currently trying it out on our family server (Mindcrack pack), and it's a pita trying to figure out what is what.
Also (and this one is clearly started, as the links are there, just there's no info in them yet) Factorization would be a great page to finish, as it's so irritating having to look up a thread in MCF (at least Gregtech has a wiki - albeit an unofficial one!) every time one wants to check something out, such as last night I wanted to find out how to make diamond shards for my wrath igniter, and also wanted to figure out routers.