There are plenty of examples both ways. I haven't denied the fact that you can likely find 100 such from your side, but don't doubt that I can do the same.
Recent events have named quite a few.
1. CBS 60 Minutes mess with Bush and his memos ... clearly a news team including the president of the CBS news taking a side in the election and going for the throat. Sounds like a left lean to me. They didn't even address the Swift Boat thing which had substantially more reason behind it then the cooked up memos.
2. NY Times and CBS sitting on the explosives story for over a year and then the Times going ahead with it with only partial facts five days before the US election.
3. ABC News memo leaked to the press in October telling his news team to essentially drop objectivity.
"The current Bush attacks on Kerry involve distortions and taking things out of context in a way that goes beyond what Kerry has done," Their news chief Halperin claimed ABC news will not
"reflexively and artificially hold both sides 'equally' accountable".
That's a clear left lean.
4. Tom Brokaw carried a story during the 2000 election when Gore representatives complained that the Bush campaign was using subliminal messanges by running a TV spot with a picture of Gore and Lieberman standing in front of the word BUREAUCRAT. They blocked out the BUREAUC part leaving only RAT. Silly? Sure, but Brokaw didn't run the story this time around when Kerry's group ran a TV spot where Bush was standing in front of a word blocking out all but the word LIED. Both are silly, but NBC was up in arms one way, and ignored it the other.
5. Lets return to CBS and Rather again ...
His comment the day after Bush was sworn into office
1/22/01 - "This was President Bush's first day in office and he did something to quickly please the right flank of his party: He reinstituted an antiabortion policy that had been in place during his father's term adn the Reagan presidency but lifted during the Clinton years"
His comments eight years earlier?
1/22/93 - "Today with the stroke of a pen, President Clinton delivered on his campaign promise to cancel several antiabortion regulations of the Regan-Bush years".
See the issue there?
Bush is pleasing his right flank, and Clinton is fulfilling a campaign promise. Showing his colours there ... I would guess the Republicans had run on an antiabortion stance therefore Bush was also fullfilling a campaign promise. Just as I'm sure Clinton was pleasing the left flank of his party. Not very consistent Dan.
6. Peter Jennings on ABC News covering the impeachment vote for Bill Clinton. During the live coverage he introduced by voice over every member of the house as they came up to vote. All Democratic members were introduced as "Bill Smith" from the great state of "Alaska", while each Republican was introduced as "the conservative" or "republican" "Bill Smith" from the "great state of Alaska". He felt it necessary to label each conservative house member, but just name the name and state for the Democrats.
7. LA Times editor John Carroll wrote the following memo to his news staff basically admitting they have a left bent to their news coverage
LA Times Memo
8. Similarly here's the New York Times admitting the same thing .
New York Times
So there ... ABC, NBC, CBS, both Times, all caught at one point or the other.
Will that matter to you? Probably not, and that's fine, but don't assume there isn't anything to back up the bias contention just because I didn't want to go to the hassle of reproducing it.