As if by magic, Apple today started releasing new versions of apps that already support the Apple Watch.
The watch will only hit the international market in a few weeks, but as Mark Gurman, from 9to5Mac, it needs to do this mainly for journalists who already have Watch units to test third-party apps on it for their reviews.
We have separated some of those already on the list below:

Evernote
in Evernote




Version 8.24.5 (165.2 MB) Requires iOS 11.0 or superior
Free

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in Twitter, Inc.



Version 8.17.1 (126.9 MB) Requires iOS 11.0 or superior
Free

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Sorry, app not found.

The New York Times
in The New York Times Company


Version 9.22.0 (110.1 MB) Requires iOS 12.0 or superior
Free

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The Wall Street Journal.
in Dow Jones & Company, Inc., publisher of The Wall Street Journal.




Version 12.6.2 (116.3 MB) Requires iOS 11.0 or superior
Free

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Sky Guide
in Fifth Star Labs LLC



Version 8.1.6 (232.5 MB) Requires iOS 12.0 or superior
R $ 10.90

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LINE
in LINE Corporation



Version 10.6.1 (281.3 MB) Requires iOS 11.0 or superior
Free

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in WeChat



Version 7.0.12 (315.3 MB) Requires iOS 10.0 or superior
Free

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Procreate Pocket
in Savage Interactive Pty Ltd

Version 3.0.6 (292.8 MB) Requires iOS 12.0 or superior
R $ 18.90

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Onefootball – Football News
in Onefootball GmbH




Version 13.11 (108.3 MB) Requires iOS 11.0 or superior
Free

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Sorry, app not found.

Expedia: hotels, flights and cars
in Expedia, Inc.



Version 20.17 (117.1 MB) Requires iOS 11.0 or superior
Free

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(Among others)
The functionalities vary among them, some are more complete and in fact bring new functions, others serve only as a bridge to bring information from the iPhone to the clock.
It's cool to see that the avalanche has started!
(via MacRumors; Onefootball tip from Leonardo Mellon Miranda)
Update · 26/03/2015 at 22:00
We added more apps (the last two) to the list.