Hi Heather:
1. Baptism vows, for one, changed in 1985 from "baptize in the name of the Father, Son, Holy Spirit" to "baptize in the name of the Father, Son, and God's Spirit-Directed Organization." (choke & gag!) That's the main one that sticks in my mind.
2. Where Paul said there is only one mediator between God and men, a man, Jesus Christ -- 1 Timothy 2:5 -- well, we know how WT 'went WAY beyond' that scripture by saying THEY are the mediator FOR US (between US and God). Ughhh, I don't THINK so! -- See also John 14:6 where Jesus said, "I AM THE WAY AND THE TRUTH AND THE LIFE, no one comes to the Father BUT THROUGH ME."
3. These next topics may not qualify as 'going beyond what is written,' but more like 'leaving OUT what is clearly written' ;-) : ie, the WT teaching us in an 'allegorical' way rather than teaching scripture literally. I have since heard that 300-400 years after Jesus, when he had not yet come back in his kingdom literally (which they believed he WOULD), that the 'church' back then got all confused and didn't know how to deal with that fact, so they decided Jesus must have meant everything he said would never happen literally, but 'spiritually,' so they quit taking scripture literally; and it seems WT bought into that line of thought. For example:
(a) The WT saying the nation of Israel was forever abandoned by God and that everything to do with the rebirth of Jerusalem/Israel is "spiritual Israel" rather than what is really is: The Real, Literal Flesh and Blood Israel over there in the Middle East! The WT completely took us down the wrong road in that respect, directiing our attention completely AWAY from what has been happening over there; telling us all the scriptures to do with Israel meant the 'JW anointed' in a 'spiritual sense' and not literal Israel in a fleshly sense. That may sound confusing, but, imho, it's really a HUGE deal and is quite simple when we remove the 'fog' of WT's convulted reasoning, ie, when God said he would bring the Jews back to their homeland and recreate that nation in 'one day', he meant it literally and he made sure it happened, back in 1948, when the 'new nation (of Israel)' was 'rebirthed' (Isaiah 66:7-9; Zechariah 3:9; Romans 11:1; Genesis 17:7-8; Ezekiel 20:40-44; Ezekiel 36:21-22; Amos 9:15; Romans 11:26. For add'l info, check out: "Modern Miracle of Israel's Rebirth," http://www.cuttingedge.org/ce1054.html )
(b) The WT teaching that the 144,000 applies in a 'spiritual' rather than a 'literal' sense, and is their JW- 'anointed few' rather than literal fleshly Jews like the scripture says! - Revelation 7:2-8
(c) For the WT to think they are sooooo 'privileged' with prophetic knowledge, why are they not teaching JWs about the 7-year literal tribulation? - Daniel 9:27, 11:31, and 12:11
(d) And there were sooooo many scriptures they applied to themselves 'spiritually' which were not accurate at all, such as: the two witnesses prophesying for 42 months, being killed for 3 days and coming back to life -- Rev. 11:1-14 (baloney, the real application of the 'two witnesses' hasn't even occurred yet); and the WT saying they are the 'burdensome stone' which all the nations are against: baloney again -- Zechariah 12:3 -- as that applies to the REAL Jerusalem, not the WT; and etc. etc. ad nauseum. You get my drift... ALL those scriptures about Israel/Jerusalem that we spent hours hearing/reading WT mags re: the 'spiritual' application of... well, they were ALL WRONG. We were sooo duped along these lines, that world news about the Middle East didn't even phase me as a JW, yet everything that is happening there today LITERALLY is in scriptural fulfillment of all these Bible prophecies.
4. Finally, and this one really bugs me... :-) heehee... The WT always taught us there would NOT be a literal, individual ANTICHRIST (which, actually, never made sense in view of 2 Thessalonians 2:4 which says he will set himself up as "THE" God, NWT). But WT reasoned that since John had said there were 'many antichrists' (plural) among them way back then -- I John 2:18 -- that 'antichrists' referred to ongoing widespread apostacy, rather than one man. That is true there were/are many 'antichrists', but there are other scriptures than speak of the One, Real, Individual, Singular Man, Antichrist, that is coming at the end of the days, and since the WT had us so convinced there was NO SUCH SINGULAR PERSON to be on the lookout for, that if we had stayed with WT, we would/could have been completely caught offguard when he DOES arrive on the scene. As a matter of fact, it wouldn't surprise me the least little bit if the WT, since it so thoroughly misleads its members on this particular subject, that when Antichrist DOES appear, they will think HE is Jesus and WT will convince JWs to follow HIM! --
In various translations The Antichrist is referred to as the Man of Lawlessness, the Son of Perdition, the Son of Destruction, the Dog of Satan, the Son of Doom, the Man of Sin, etc. (sounds like ONE MAN to me). Some speculate he may be a homosexual due to the scripture at Daniel 11:37. He was also explicitly described by Daniel AND Paul. They describe how he will use craftiness/deceit/intrigue/dark sentences/etc. to destroy many when the people are 'taking it easy,' they are 'at peace,' he will 'catch them off-guard' and 'without warning' he will 'destroy many.' -- 2 Thessalonians 2:2-13; Daniel 7:25 (the 11th horn); 8:20-27; Dan 11:21-45; Revelation 13; 1 John 2:22; etc.
That's my soapbox for now. I was just reading again about this stuff earlier today, so that's why it was right on the top of my mind.
HTH!
Grits