Yep! I have made/modified a few things too.
Same thing as you (Lisa) regarding sleep system. I could have bought a "hostel" sleeping bag from Mountain Equipment Co-op (MEC) with cotton sheet one side and a quilt on the other but it also has a zipper and I can't stand the confinement of a traditional sleeping bag. Besides, the zipper is added weight. I simply sowed the very bottom edges together of the silk/fleece and about 12 inches up each side so things won't slip/slide away. I have also added a small pocket to keep ear plugs, head lamp and prescription glasses in a safe place/easily accessible (one small pocket on each silk/fleece sides so they are on the bottom no matter which side of the system is up). Best part of my home-made system - it was less expensive and lighter than the MEC version... win-win!
I have also made adjustments to my pack - the biggest being that I moved down the shoulder straps. I ordered the right size of the GoLite Jam 35L based on their website measurements but when I tried it on, it was just slightly too long in the torso. I think the next size down would have been too small, so I tweaked a bit and now its perfect. It's like I'm not wearing a pack at all
I'm also thinking of camera and sunglasses pockets on shoulder/belt pack straps - I guess great minds think alike - or perhaps incorporating in my "never-leaves-my-body-because-of-important-stuff-inside" bag that I want to make (for passport, credential, cash/cards, phone, camera, notebook, pen), since I have not yet seen something ready made that fits my "vision". I'm thinking of something that clips on the front of me to perhaps the shoulder straps of pack and converts into a purse-like bag when not using the pack... the closest I've seen is this
http://www.zpacks.com/accessories/backpack_lid.shtml but I don't like the look of it and it's a bit too big for what I want to put in it. I have a few months still to experiment/test
I've also made a sarong type wrap based on the Bina Brianca wrap:
http://truebluemeandyou.tumblr.com/post/23930934960/diy-bina-brianca-knockoff-two-tutorials. This thing has soooo many uses, well worth its weight IMO, especially since I will be going in October, this is also an additional "warm" layer to day wear and night time sleeping system.
Last but not least, you'll think I'm crazy, but I have cut out all manufacturer tags, extra doodads, dangling things, zipper rope pulls and useless extras on all my stuff (including shortening the ridiculously long straps on my pack - just make sure you melt then ends so they don't fray), and managed to remove 254 g/9 oz of USELESS weight - almost the weight of my two t-shirts!!! not so crazy now... right?
I would also like a way to access/store my trekking poles in a way that I don't have to take my pack off. They fit really well in the side pockets of my pack but I have to take it off to access them/put them away securely (I would hate to have them fall out while walking and not notice). The wheels are spinning as we speak and will be testing some options in the next few weeks.
I'm having so much fun planning, modifying, testing, thinking, improving....