ADTRWiki is a wiki set up for members of the Something Awful forums to recommend and comment on anime and manga. It offers members a chance to contribute synopses and reviews for series, in order to help people find stuff to their tastes!
You can find the ADTRW FAQ at ADTRW FAQ,
How can I contribute my opinion?
Opinions can be added on series pages by clicking  next to the "Personal Opinions" header near the bottom of the page. Then type three equals signs, your name, and another three equal signs, followed by your opinion on a line below. Make sure to save! You can find editing help at Help:Editing
How can I add a page?
Adding a page to the wiki is very simple: Use the search bar on the left to search for a series that you would like to add. If a page for this series has not already been created, you will be told that the page does not exist and given a prompt to create it yourself. From there you can start to create and edit the page for that series. From there please see the template to bring your glorious dream into reality!
"I am new to anime/ manga, or don't know where to start."
Anime is quite diverse; tastes for it vary as much as tastes in anything else. It can seem daunting if you have new-found interest in the medium to figure out where to start.
To that end, we've compiled a nice list of good "intro" series. Please note that these category classifications aren't absolute (many of the action series are also sci-fi, so forth), and that these are certainly not the only good series out there. Read the series summaries, along with commentated opinions, to see if they are something you might want to try!
Many of these series are available via Amazon, though some have not been released domestically; for these, you'll have to search for them via torrenting or other means (see the ADTRW FAQ).
In addition to these series listed, you may wish to check out the works of Hayao Miyazaki, Mamoru Hosoda, Satoshi Kon, Mamoru Oshii, and Masaaki Yuasa the output of which is almost all uniformly good. You may wish to also look for anime adaptations for some of the series below (though not all...)
"I have fell into a time hole for the last few years! I want to know what I missed while I was gone."
Well, tastes as ever vary, so you might want to consider looking at series suggestions on the pages for the series you already like.
Beyond that, we do often have yearly votes on our favorite series for the year. You can find a listing of the results of those here.