Giant resume directory LinkedIn has launched a new site to host its technology experiments, called LinkedIn Labs, the company announced today. At launch, Labs contains four experimental products. One is good, another in closed beta still, the third a disappointment and the fourth will be of little interest to anyone who doesn't work for the company itself.

In other words, this incredible site, so full of potential for analysis and technology that adds value to the lives of users, has fallen short of that potential again. Time and time again LinkedIn disappoints in two ways: it fails to cut to the chase and tell you who has a new job and it insists on trying to be more like Twitter than it ought to be. It's really a shame, a LinkedIn Labs could be fantastic. You should go try to get into the beta of LinkedIn Signal though, before the 500 invites the company extended today expire. That's worth checking out.

At launch Labs contains four experimental products. The company says in its announcement that visitors may find short-lived efforts there, that some Labs projects may only live for weeks, but in reality the initial offerings are more tame than experimental.

NewIn 2.0 is the name of the first, and it's a Google Maps and Earth visualization of new users joining LinkedIn around the world. That's a toy for the marketing department, not a technology anyone else wants to use.

ChromeIn is a Chrome extension that lets you read and post updates to and from your LinkedIn contacts. That would be great, if it would just show me an alert and some details when a contact of mine gets a new job, or when a company I am tracking makes a new hire. Instead? It's just a second-rate newsfeed filled with recycled Tweets. That's worthless. Relative to the potential that such a tool has, it's almost offensive.

Instant Search (pictured above) is a dazzling and useful people search interface. It's great. It should be an option on the live LinkedIn site, but for now it lives in labs. Someone's probably afraid that the stuffed-shirts just starting to use the site would be frightened by the rapidly changing search results.

Signal (pictured, below) is the company's faceted search product, it allows you to search content shared by your contacts and limit those searches by industry, your relationship, etc. It looks interesting, but is in closed beta so you probably can't use it. The company is making 500 beta invites available via this link and that product really is worth checking out. It might make me change my mind about the relationship between LinkedIn and Twitter. I've always been annoyed by seeing Tweets imported into LinkedIn, but the fact that I can see who I know in the PR and Marketing industry has Tweeted about Mad Men in the last 12 hours is pretty cool.

Honestly, am I the only person who wants to love LinkedIn but struggles because it doesn't give me what I want? It drives me crazy, and the new Labs is just the latest chapter in that maddening story. A couple of these products look interesting, but they still aren't what I want the most: a news flash when someone changes jobs. That's what LinkedIn is about, is it not?