For Kansans, the priority statewide races are Governor and Attorney General. Don't ignore Insurance Commissioner and Secretary of State, but giving the state 4 more years of successful leadership by Governor Sebelius and replacing the lunatic antics of Philllll Kline with competent and experienced law enforcement by Paul Morrison is important.
My guess is that the 3rd District House race will not be as exciting as it has been in years past, but Dennis Moore will still be facing stiff opposition funded by the National Republicans, no matter which third-string candidate wins the primary. Contributing to him now will help convince the NRCC that they should leave that district alone.
The big House race will be in the Second District, where Nancy Boyda is working to bring democracy back to the People's House. That's the race that will be bloodiest and where cash infusions early and often will do important work in making Jim Ryun actually work for the people of Kansas, rather than for Tom Delay. Be sure to enter "Josh Rosenau" as your 20/20 team leader.
If you don't have a strongly contested House race near you, you should consider kicking in for this campaign. It's likely to be a race you'll hear more about as November approaches, and success in that district will be a bellwether of how the push to take back the House is shaping up.
Of course, you should never ignore your local races. Check in at Our Congress for updates on your local race, and if you don't see entries for it, start contributing. Check what's being said about your local races at DailyKos and MyDD. Both have extensive sections for user contributed diaries, easily searchable by district, so try searching for something like KS-03 to find out about Dennis Moore, or NJ-07 to find out about attempts to unseat the horrendous Mike Ferguson. Lucky dogs with contested Senate races can use the same resources to get vital background on candidates, especially if there's a primary.
Google is a great tool, but having that background for your local race can help you sort out the wheat from the chaff, and even helps you skip over the often confusing mess of names that comes out of Google.
Once you start to have your favorite candidates, it's not a bad idea to head over to ActBlue for a unified way of contributing. For instance, here's the handy page of all the statewide candidates in Kansas. You can create your own list of favored candidates and send it to friends. You can see my list right here. Contribute to it if you like.