I don't think that's a good idea. Yahoo has a problem that it's divisions seem to be too diverse and unintegrated. Buying even more will lead to a further lack of focus. Purchasing several web 2.0 apps will lead to a fragmentation in the attention span of the people managing these properties. You also need to allocate engineers to develop each item.

What Yahoo should do is own several large sites, and monetize them across a single integrated brand per site. For example, flickr and the Yahoo portal are two large brands.