To clarify, some gifts are for ordering from mu-mo.net and you don't need to be TA members to get them. TA members will usually get a bonus gift in addition to a mu-mo.net gift. Most CD's recently also come with posters for first-presses. Sometimes, concert venues offer a gift when you buy CDs or DVDs there.

I only know some of the more recent freebies because I have them:

Days/GREEN
poster (first press)
notepad (mu-mo gift)
We <3 Ayu keychain mirror (TA bonus)

Sunrise/Sunset
poster (first press)
flip-flops (TA)

Rule/Sparkle
dress sticker (for Suica cards, etc) (TA)
memo pad (mu-mo)

NEXT LEVEL
clearfile + notebook set (TA)
jacket size sticker (mu-mo)

Premium CDL DVD
stickers (mu-mo)
coaster set (TA)

You were.../BALLAD
poster (first press)
Christmas postcard (mu-mo)
fleece blanket (TA)

I have another sticker sheet and a clearfile, too, but I don't remember which order it came with (possibly Asia Tour 2008?)

Oh, and TA members get a gift each year they are with the fanclub. When I joined in 2008, it was a bandage set. Last year it was a gold passcase.