Anyone else get a check from researcherpanel.com?

[weepy]

I got a $20 check in the mail today from researcherpanel.com and have no idea when or through what website I signed up under (like-was it under one of the points programs or something?). Does this ring a bell with anyone? I tried to log in the site under my top three e-mail addresses (I have one for everything I do-so I have about a million e-mail addresses) and I couldn't get in, so I figured if I knew how I signed up for this, I would know what e-mail I used. Anyone know anything about this site or get a check from them?

[brainstuff]

Hi, I have also one of these checks ... received now .. issued 8/31/2000 ... but I find not this company ... the interent site seems to be closed .. do you know if US checks are valid after 6 years???