Minecraft and it's mods, suggestions please.

[Darmalus]

I'm having fun on my friends server in Minecraft and felt like branching out into mods we have installed but never used. We are currently using the 1.6.4 FTB Monster pack with Tropicraft, Pneumaticraft, Witchery and Minecraft Comes Alive added as well.

So I'm looking for suggestions on what mods to play around with, specially ones that might be overlooked gems. For a lot of these I'm not truly sure what they are capable of. I ignored bees for the longest time, but now I'm stumbling my way toward automation and engineering some super-bees. The mods I'm using heavily right now are Rotarycraft, Bees (my god), Thaumcraft, Tinkers Construct, Magic Crops, Mystcraft and and tinkering with Witchery and Pneumaticraft, thought I've yet to dig into them too deep yet.

Thanks to abusing Magic Crops, Mystcraft and quarries, we have a pretty massive resource glut. No need to worry about the resource cost of a suggestion, the only limit is how much time I have to play.

[Lagmonster]

I'm a big fan of Hexxit and Tekkit (featuring Galacticraft), available via the Technic platform (which I personally find a great place to get modpacks). Hexxit especially pulls in good fun in my group because of the emphasis on exploring and knocking out dungeons and bosses for loot.

[Mr Bean]

You already have everything on my list.... except the Twilight Forest

[Terralthra]

Mekanism and MachineMuse's Modular Powersuits (with the extra modules pack) are my two favorites. Applied Energistics is a lot of fun. Extra Utilities and Random Things both add a lot of utility.

[Purple]

I play FTB my self. However I use the ultimate pack and the only additions I have made to it is adding MoCreatures. I know it's silly to stay behind the versions but I just can't live without redpower. So that's my suggestion for you.