I have a slightly hacky solution for creating an IFTTT timer / delay; I'll use the wemo as an example:
When the wemo turns on, have another recipe to detect that and create a google cal event via the google cal channel. Here's the key, use a google cal with the time zone set behind your actual time zone. Eg if you're in the Eastern time zone, set the cal to Central. I use the Google quick add, and make sure to use a unique keyword in the event, eg #wemoturnedon
Now that you have events being created in Google cal. by your wemo, you simply setup another google cal recipe to look for that event. Use the search trigger so you can specifically find the #wemoturnedon keyword. The recipe can then be set to turn the wemo back off again.