I've heard a lot of people complaining about AP itemization over the past few weeks.
And as a big fan of alternate game modes, I'd like to invite you to a lesson about Twisted Treeline!
We have two weird AP items that I think you guys on Summoner's Rift are missing out on: Wooglet's Witchcap and Moonflair Spellblade. They fill niches that are sorely missing on Summoner's Rift, and if RIOT were to ever transfer them over to our bigger, more familiar map, I think you guys would find that they really help with the diversity issues.
Wooglet's Witchcap is an alternative to both Zhonya's AND Deathcap. It has 40 armor and a stasis active, but less AP and a weaker passive AP gain than Rabadon's, at only 100 base AP and 25% passive AP gain.
Now some of you might be thinking that a stacked Deathcap and Witchcap would be overpowered, and you're probably right, but I have a solution to that! Make it a named passive. Bingo. Done. The Stasis active might need some tuning, though.
Next is an item that I think a lot of AP battle mages, tanks, and fighters (and maybe some mages who are getting bullied hard in lane) would really like: Moonflair Spellblade. Now, this item is quite unique, as it provide both armor and magic resist, WHILE ALSO GIVING YOU AP, an offensive stat! It's a great all-around pickup at a reasonable cost. But more important than any of these qualities is its passive: TENACITY. It would finally provide an alternate to Mercury Treads in terms of reducing crowd control. Not only that, but it's Tenacity is also slightly stronger, 35% compared to MT's 30%, which isn't much, but is still appreciated.
Now, to get serious, this is not an in-depth look at item diversity, and I'm sure that these items would have problems of their own if introduced to Summoner's Rift. However, the point of this thread is to introduce ideas to the community (and may if we're lucky, Riot) about increased diversity and note that we already have two interesting items that have potential for freshening up AP itemization.