Advanced Power Management
http://forum.industrial-craft.net/index.php?page=Thread&threadID=7900
It's extremely convenient when you need to charge a lot of items at once or for storing multiple items that you want to have charged and able to use. I like to treat charging benches as a chest for IC2 tools.
I was going to recommend Charging Benches but I believe that mod went inactive and isn't being updated anymore. This mod may actually be more balanced and convenient since it requires you to use a batbox/mfe/mfsu to craft and then it stores energy as well.
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Transformers
http://forum.industrial-craft.net/index.php?page=Thread&threadID=5789
I typically like to focus a lot on IC2 more than the other mods. But this mod actually makes me want to branch out a little more. With this Buildcraft gains a lot of interest to me. It's really fun being able to make basically large electric generators using combustion engines feeding into a MFSU so that it's easier to store for later and then transfer that into an electric engine.
This mod I think would make a great addition to the pack. I've been making due with forestry's electric engine but it feels slow and very lacking in options. I mean you can alter it's output with circuit boards but there really isn't a lot of variance, plus I don't believe there are really any ways to convert MJ into EU effectively yet. Also this mod shouldn't be unbalanced since all the conversion rates can be adjusted in the config.
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Lastly, I'm just curious why Charging Pads weren't added to the pack. After looking at the page it looks like it'd be a nice addition to FTB. (Sorry for posting this right after another person brought it up, just saw that it wasn't going to be added to the pack after checking for anything relating to charging)