one was an eastern european who worked in my office and who i thought would kick my ass. turned out, he was hideous at it but kept telling me how bad he was going to take me down the next time. never came close. the other was a scandanavian who i played completely by accident. beat him but i think he was a teenager. after the company we were working for folded, i never played online again. chess.com has some really excellent puzzles that help a lot with spotting tactical moves and trying unusual moves to gain an advantage. i always do the "daily puzzle" and then the 5 free "puzzle" quizzes they give you each day. my current rating there is 2600+, so i'm reasonably satisfied with that. anyway, i don't trust online. when people paint themselves into a corner, they have difficulty accepting it. that's natural. some just use the computer against their opponents to boost their ego.
over the board is the only legit way to go, imho.