Has anyone tried offering time-limited but otherwise full-featured versions of their games for a reduced price? Obviously this approach wouldn't work for games with low replay value and it begs for someone to crack your game, but might it work for games that have high replay value (eg., mahjonng)? I guess what I'm proposing is renting software. Is this just too wierd for people?

I've actually been a consumer and I've rented games. Mostly from eb1.com, real.com and gamesondemand.yahoo.com
Both eb1.com and real.com's rental service has since then gone out of business! I never liked it, because it was so expensive. For instance it was 5$ for 3 days in eb1.com. The actual game was selling for $15 on ebay!