It must be momentum week at Seattle startups, which are releasing all sorts of tidbits. They include:

-- Mixpo, an online video ad platform, announced partnerships with five big publishers that will now use Mixpo's VideoAd technology: NBC Local Media, Tribune, Freedom Communications, TownNews.com and Fisher Communications.

"We share the conviction that it is at the local market level that customers want to engage, and where advertisers want to be present,'' Mixpo Chief Executive Anupam Gupta said in the release.

-- Avvo, the online legal directory, rating and referral service, announced that it's now getting more than 1 million visitors a month. Founder Mark Britton said the company's also hiring three people -- two sales reps plus a coordinator -- to ramp up the ad platform it launched in November.

-- WidgetBucks announced the general release of YieldSense, its technology for automatically displaying its best-performing widget ads on participating publisher sites. The company said more than 20,000 site owners and bloggers are using its ad network.

-- A group of friends in the tech, social services and healthcare fields created 44ree.com, a Web site where people can trade or donate material. The idea is to "promote a green-friendly environment through recycling while giving back to those in need,'' co-founder Joseph Rogel said. The site formally launches next month, and a portion of the company's profits will be donated to charity. It sounds like a competitor to Martin Tobias' Kashless.com barter site, and both will compete with Craigslist.

-- It's beyond the startup phase, but McObject, the Issaquah-based embedded database developer, also announced the release of its Perst 4.0 embedded, open-source database. It includes new tools for developing on the Android and Java ME platforms.