As expected, Democratic candidates would take several House of Representative spots previously held by Republicans. Currently, 20 seats have been gained and there are 7 races that are still too close to call.
New York Times

Washington Post

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Democrats picked up at least five Senate seats, but missed their goal of acquiring a filibuster proof majority (60).
Highlights for the Senate races (work in progress):

3 races remain too close to call: Alaska, Georgia, and Minnessota
In Minnesota, incumbent Republican Senator Norm Coleman held off challenger Al Franken, however less than 800 votes separate the [...]

The voters have spoken and Barack Obama will be the next president of the United States.
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Electoral College:
Obama: 365
McCain: 173

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Popular Vote:
Obama: 66,617,824
McCain: 58,164,524
results still coming in…

 Indiana can give clues as to how the election will unfold, in particular Vigo and Hamilton county. View the 2004 county map below and then visit the current map. (via New York Times

New York Times 2008 Election Results (president, house and governor)
Vigo Co. bellweather of U.S. voting

2004 Election Map in Indiana

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The polls start closing at 6pm eastern time in Indiana and Kentucky and by 7pm polls will be closed in Virginia, Florida, Georgia, South Carolina, and Vermont. Ohio and West Virginia close at 7:30 and at 8pm polls close across the country from Texas to Maine. More than half the country will have [...]

In addition to the presidential election, there are 435 congressional races, 35 senate races, and 11 gubernatorial contests to keep an eye on. Here is a round up of some of the best guides to watching the 2008 elections. (will be updated through out the day, so be sure to check back)  
What to [...]

The Washington Post has another map out in their Political Geography series, this time examining the key swing states in the 2008 presidential election.
A state-by-state breakdown of how Barack Obama and John McCain are expected to perform on Tuesday.
click for interactive full-size map

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Our Vote Live.org is tracking voting problems being reported during the November 4th, 2008 election and has several maps showing where the problems are occurring, both at the state and county level. .  
The maps below are from 11:30 AM EST, but already show that there are a lot of voting issues accross the country. [...]

Today’s op-ed in the New York Times looks at how the electoral college used to determine the president of the United States disproportionately favors smaller states. For example, 1 electoral vote in Wyoming represents 134,783 voters, while 1 electoral vote in Pennsylvania represents 456,216 votes.
This map shows each state re-sized in proportion to the [...]

With one day before the 2008 Presidential election, Barack Obama appears headed for an electoral map changing victory over John McCain. McCain now finds himself defending traditional red states and hoping for a way to pull off an upset.