Here’s what I’ve been able to find:
Name Tw- Day Translation Corporation
Country Taiwan
Contact Name Andrew Chang / Chee Chang
URL tw-day.com.tw
Address 6F.-6, No. 220, Songjiang Rd., Jhongshan District
City Taipei City
Postal Code 104
Phone +886-2-2571-6086
Fax +886-2-2571-6087
Agency has a perfect score from freelancers so far on ProZ.com; the only thing that strikes me is that all the four positive comments sound so much alike…but that might be legitimate. Four freelancers have rated the agency as “5” (very likely to work for them again).
It’s listed as a member of the Translation and Attestation Assn of Taiwan, for what that’s worth (127 members, don’t know what the criterion for entry is):
Translation & Attestation Association of Taipei
6F-20, No. 121, Chungching South Road, Section 1, Taipei, Taiwan
TEL: +886-2-2370-9786 FAX: +886-2-2370-9785
They seem to do mostly manuals into “rarer” languages, plus work into Japanese. I see Acer manuals and Skype manuals on the list of projects they’ve sourced in the last six months. They seem to be fairly new – first job I can find they’ve sourced a translator for was October 18 2005.
HOWEVER – a very recent bid asked for a “native Traditional Chinese Translator” to work into English on a 29,000 word job, for a fixed payment of US$550. That’s $0.019 US dollars a word – about NT$0.03?? RIDICULOUS. Even for a native Chinese speaking translator in Taiwan, work into English should be around NT$1 MINIMUM, assuming it’s a tight-a@@ed agency giving it out. 
Another recent job (December 2005): “Fixed pay of USD 535 for each 30,000 word document.”
So – if you can make some money off of them, fine, but I would strongly advise you to use caution and keep a calculator by your side! Unless they are suddenly trying a different business model, they seem to be aiming to use the cheapest possible translators, and as a native English speaker in Taiwan, do NOT let yourself be sold short. If you’re not making NT$3 per word for translations, they’re making too much off you. OK, maybe NT$2 to an agency if you’re in a good mood. 
And if they’re hiring you as an editor, you’re going to be cleaning up the mess they get from translators who will accept ridiculously low prices to “translate” into English. 'Nuff said.
Just my NT$0.66. I hate bottom feeders, and at those prices, I’m afraid I’m going to characterize these folks that way.