These sites offer some easy ways to earn a little extra money.
Swag Bucks - This is my favorite spot for earning. It has great gift cards available, including a Paypal option to get straightforward cash. The best part is I don't do much. I just use their search engine once in awhile.
Opinion Outpost - A fairly clean, easy to figure out survey site. They offer 'Opinion Points'. 10 points = $1, and most surveys I've seen offered at least 10 points.
Vindale Research - You can do surveys, studies, polls, etc. and get paid via Paypal.
Inbox Dollars - I usually use the paid e-mails on here. I do surveys and other things if I see anything interesting.
SendEarnings - I basically use it the same way I use Inbox Dollars.
i-Say - Awards points that you can redeem for cash, Amazon gift cards, etc. Even if you don't qualify for a survey they'll give you points for looking at it.
Survey Savvy - Another straightforward one that rewards taking surveys with cash.
MindField Online - Cash surveys. You can get paid via paypal or standard check.
Valued Opinions - Yet another one that offers Amazon gifts cards and other things.
CashCrate - They have a few free surveys every day. You can also sign up different places to get money. Be careful what you sign up for.