One measure of a service’s utility and stickiness is its ability to charge for usage. Consequently, I regularly find myself asking, “Is this important enough to me that I’d pay for it?”

Here are some of the services / sites where that answer is yes… And what I’d be willing to pay:
Gmail: I’d pay to keep my Gmail account more because the switching cost is high than because of the functionality. That switching cost is painful enough that I’d spend $75 to prevent it. I will likely end up paying for increased storage too.

Google Maps: Love Google Maps for my Blackberry. Telenav is $9.99 / mo and offers greater functionality – I’d likely pay $10 to download Google Maps or some nominal monthly fee. If Google Maps added navigational directions, I would pay $10 / month.

WordPress.org: The benefit of blogging with WP is so significant (SEO, functionality, flexibility) that it’s well worth paying for. I’d probably pay a $200 for an installation… which makes me realize how much I rely on the product.

Google Analytics: If Google analytics weren’t free, I would unhappily pay a monthly fee to install it ($10) because, despite my disdain for the interface and lack of real-time metrics, it really is a necessity.

Google Analytics w/ Real Time Data: I would certainly pay extra for real-time Google Analytics.

Slimstat: Slimstat is a free WordPress plugin that delivers real-time analytics. I would pay $40 to install it.

Slimstat “Premium”: … And I’d pay a lot more if Slimstat offered a model with unlimited data capturing / storage (the basic one shows the last ‘n’ records). I would pay $100 / domain.

Mint Analytics: I gladly paid $40 to install Mint on my domains. Great data and great interface.

Craigslist: I would pay for premium listings on Craigslist (if they introduced some sort of featured ads format) and I’ve paid the jobs listing fees before (many times).

Amazon Prime: I spend enough on Amazon that they gave me Amazon Prime for free when it first launched. Considering that I buy my groceries, toiletries, electronics, dog food, etc on it – I’d pay for Prime if Amazon forced me to.

iStockPhoto Premium: I love iStockPhoto – but it’s a pain to purchase credits. I’d pay for a premium account that enables power-usage.

MLB.tv: MLB is the only major sport that has truly adopted the web and their radio and video streaming is fantastic. I already pay for the service (estimates: $14.99 for radio broadcast of all games,$99-$179 for video)

Podcasts / On-demand Radio: There are certain podcasts and radio shows that I would pay to be able to download in entirety. For instance, I love The Thundering Herd on ESPN Radio but it streams too early on the west coast for me to catch it – and the Podcast only captures 30 minutes of the broadcast. I would pay $5-$10 a month to listen to it on-demand, in its entirety (price depends on whether or not ads are in the broadcast). The same can be said for Tony Bruno and JT the Brick.

eLance: I love eLance. Use it all the time. They choose to charge the service provider – but if they reversed it, I would pay on a per-listing basis. The price depends on the project, but a nominal amount ($5?).

ESPN360: It’s the only way that I can catch Duke games without leaving work at 3pm pst… I’d pay either per game or per month ($5-10) for the service. I’d pay a whole lot more if they could include MLB, NFL and NBA (would start to challenge my Comcast bill).

Popularity: 7% [?]