As far as the website promotions:
Within the on air "mention" itself you can say "more information (is at) kxkk.com (or their own website)" I would refrain from saying "pricing and coupons are available at kxkk.com"
By all means promote the heck out of your website! That is where you can legally have all the ads you want!
Remember too that the only organization you can raise money for on-the-air is for the station itself. You can't have a pledge drive for the ASPCA.
I am still thinking through the legality of a non-comm having a radio auction in which the station sells goods donated by businesses to the station. It would get the products on the air with a retail price and sell them. However, it becomes tricky to not draw the line between product donation = money for airtime/promotion. Although, when the items are donated, they become property of the station. The station could raise funds for itself by selling off its assets including microphones, towers etc, or $50 gift certificates to a spa over the air. The product language and description (including price) could be read to help describe the item. Of course this could all be done on the web through an ebay account too. (don't sell promotional cds!)
If the radio auction would be illegal, I wonder if a Tradio or trading horn program on a non-comm be legal. It might be seen as raising funds for individuals. Of course the individuals would not be paying for airtime.
By all means use the internet, a sponsored weatherline or concertline. Make sure every weather forecast is sponsored in part by _____.
Sponsors for specific shows must be announced "during" the show.
General station sponsors (for the upkeep and running of the station) do NOT have to be mentioned, but can (and should) be mentioned whenever the station is on the air.
Also, you can run commercials on non-comm stations as long as the station receives no money, no promise of future money or sponsorship, no donated items, NOTHING at all. The FCC has dismissed illegal underwriting mentions when the station received NOTHING for the mention (time=infinite). Be very careful!! (there is an FCC target painted on this idea, but they can't charge you with selling airtime if you give it away and receive nothing for it) This would allow you to air professional sports feeds (still this might be a bad idea)
However another interesting idea:
Only the main signal (99.1) must be non-comm. The SCA's can be sold, rented, or even ran as a commercial radio station! This is exciting considering DRE Digital Radio Express makes a digital audio feed using the SCA. You could create a commercial radio station and piggy-back it off of the analog non-comm signal.
Going on a limb here, because HD radio is not the main signal of the station, you could run 3 commercial feeds on the HD channels of a non-comm. Recently, the FCC has allowed translators to retransmit separate HD (HD1, HD2, or HD3) feeds as their main feeds. If you get a translator above 91.9Mhz, you could feed it with one of your commercial feed (HD1, HD2, HD3) of a non-comm station! You could also let a translator pass your HD+analog signal through too.
These are some ideas of dancing on the fence! (don't fall off!)