Advanced Machines don't know how to say no to items in its fuel slot.. I usually just stick a piece of bread or something in there, something that won't ever actually come through the system to be processed.
As of 1.4.2, red bricks from the BiomesXL mod are transparent. This means light will shine through them like glass. I used red bricks in a pattern on my floor and didn't have to use any extra lighting downstairs because the sunlight passed right through. You can also sit them above solar panels and the panels still receive sunlight.
4 Creosote Tanks, 3 Blast Furnace, and 2 7x7x8 Iron Tanks lagged my game hard. Something about multiblock structures? Not entirely sure. I took them all out and I'm back to a much more acceptable framerate.
Whenever you find a village, look for the beekeeper's house- it's made partially with cherry wood so they stick out. Most of them have two apiaries, sometimes with frames and sometimes with bees. I don't think I've crafted any apiaries, actually. And the Beekeeper villager's usually have great deals (2 wheat for a Mysterious Comb? OK!). The best deal to look out for though, is an emerald for some amount of proven frames. These are the best frames you can get for beekeeping and you can't make them yourself (so I've read). I usually buy them out when I find them.
A bug in the FTB Beta pack- magmatic crucibles + magma engines. Once you get a diamond drill and a lappack, head on to the nether and blast through netherrack. For a more effective trip, bring a bunch of digger's backpacks.. I made about 8 for this occasion (that's 110 stacks of netherrack!). Just dig until you run out of energy on your lappack. The trick is that the magmatic crucible uses 4000 MJ to turn 1 netherrack into 1000 mB of lava (1 bucket's worth). This bucket of lava will then burn for 18000 MJ in a magmatic engine.. That's 14000 MJ extra! Talk about conservation of energy.. One crucible can run up to 18 engines at full capacity, although if you don't manually start a few of them with buckets of lava it'll take a while to get them all up to operational levels. Just feed 6 of the engines back into powering the crucible and you've got 12 magma engines running at 4 MJ/t, so 48 MJ/t extra energy. Enjoy it while it lasts! This exploit has already been handled in newer versions of TE.
Mining with Steve's Carts: Generate a Mystcraft age with wooden tendrils and let your mining cart go free. It will keep itself fueled with logs! For bonus mining action, generate a mushroom island single biome world, where hostiles don't spawn- even in complete darkness! Bonus bonus, put mineshafts in the age and you've now got free tracks!
That's probably enough..