Note: These recommendations are non-sponsored. I revieve nothing for my endorsement and only endorse what I genuinely like.
GNU/Linux. A quite stable OS with good features and is very low cost. Comes with many many many free and powerful applications included on the disc. Not exactly what I would call a modern OS, but better than anything else I've seen in the mainstream (eg: MacOS and MS-Windows are equally or more archaic). I generally refer to it as "The least worst OS." Not so much the future of computing as what the past should have been. Microsoft (and, to a lesser but significant degree, Apple) have knocked at least fifteen years off the development in the software industry and we're only just catching up to where we should have been in the mid 90's.
If you are new to Linux, try to get hold of a good book (or PDF) on how to use it. It will be well worth the investment. Linux isn't difficult, but it does sometimes do things differently to what you might be used to. And definitely read this: Linux is NOT Windows.
Speaking of Linux,UnixStickers make a nice range of stickers to replace that "Powered by Windows™" sticker that is redundant now you are happily enjoying the benefits of free software. It seems they donate a portion of sales back to the relevant free software projects too, which is doubleplus good.
The Stainless Steel Shop - excellent Australian source of stainless steel nuts and bolts, and - most importantly - short lengths of stainless steel: for when you only need 1m, not 6m! Note: because 1m lengths can ship in a regular courier van, while the materials are a bit more expensive pre-cut, you save an awful lot on delivery, on top of not ending up paying for many metres more materials than you might need! (They also appear to do 3m lengths of their stock, which would likely need a courier truck, but not a huge one).
A really good vacuum cleaner like the Nilfisk Coupé Neo. It sucks like a vacuum cleaner -- which most cheap supermarket/superstore vacuums don't! It was a pleasure to use, mainly because it made the job so quick, and I could see it was picking up all the dust as I went, including dust that my last few cheap-crap vacs couldn't get without my manual intervention. Well worth the little extra I paid (and it wasn't really that much more anyway). I got mine from the VacMart store on Flinders St. Wollongong -- a specialist vacuum-cleaner shop that sells to professional cleaners too, so they actually knew enough about vacuums to sell me one that suited my needs well. And I was soooo glad when the cheap one at work finally died so I could buy a decent one to replace it with. Who has time to push a vacuum cleaner back and forth for half a morning when a good vac will do the work in 5 minutes - my time is too expensive to my employer to justify that when there are high-value/skilled things I can be doing for that pay instead! - I didn't get the Nilfisk Coupé Neo this time as that one isn't warrantied for commercial use, but the shop sold me a similar one that was just as good and workplace-warrantied.
Bam! My favorite cleaning product:
Pseudodictionary - the dictionary for words that wouldn't make it into mainstream dictionaries
The Simplified Spelling Society - English spelling reform.
Meanings of First Names and First Names from Meanings
PROJECT GUTENBERG - Free Books On-Line (mostly fiction, mostly old classics).
New Scientist Planet Science - the online version of the prestigious British science magazine.
Urban Legends Reference Pages - there is a lot of stuff on the 'net that simply isn't true. And some that is!.
StartPage - WebSearch without the tracking.
Why Open Source Solutions Are Better - look at the Numbers! - open source software propaganda.
Great Microprocessors of the Past and Present! - history, very interesting stuff.
Schlock Mercenary - Original Sci-fi, fun to serious.
Freefall - Original Sci-fi, fun.
Irregular Webcomic - Lego Comic, Various themes.
Unspeakable Vault of Doom - Lovecraftian humour.
The Order of the Stick - Roleplayer humor
xkcd - A webcomic of romance, sarcasm, math, and language
The Darwin Awards - cleaning the gene-pool.
Blakes 7 Fan Site - BBC TV Sci-fi show from the 70's.
GURPS: Generic Universal RolePlaying System - Game.
Alex's paper airplanes - Instructions to make paper planes.
Lojban - a language based on logic structures. Root words derived from many languages, but mostly English and Chinese.
The Shaw Alphabet - a phonetic alphabet for English. Unicode Proposal.
Ido - a modernised Esperanto derivative.
The Play Ethic - leisure in the modern world.
Critical Thinking for atheists.
Wait But Why - interesting points of view on various topics that interest me.
Hyperbole and a Half - Depression Part Two - A good little blog-bit about depression.