There's a lot of negativity out there towards LNKD and its valuation. But then, many of these same people were also negative on YHOO, EBAY, CMG, PCLN, GOOG, BIDU, MA, V when they came public, on valuation concerns. Cramer didn't like BIDU until much later. He wasn't promoting GOOG when it went ipo, until it was trading around $300 or so, if I remember correctly. He certainly wasn't hot and heavy on Mastercard (MA) when it went ipo at $40. The fine folks who are now pooping on LNKD are also likely the same people who didn't like the YHOO's and EBAY's and BIDU's of yesteryear, until most of the stock gains were made.
I think LNKD is a good investment worthy of a few of your dollars, once the frantic trading settles down a little bit (maybe within a week or two). Likewise, Facebook, Groupon and Twitter will be good investments as well when they go ipo.
The key here is to put a little bit of money into the leaders. LNKD certainly qualifies as a leader in their field. Remember, all great stocks start with an ipo. The leaders may look expensive on their first day of trading, but several years down the line most people will wonder why they didn't buy the 800lb gorrilla on ipo day. How many people wish they had plunk some money into BIDU ('The Google Of China") on its first day of trading? BIDU is now more than a 10-bagger.