There was an article a while back about how time doesn't convert directly to money, at least in terms of an hourly wage. It's essentially the same problem that shminux mentioned.
It's still in principle possible to put a monetary value on marginal increases in available time, though, and might be practically possible in some situations (like shminux's contract work). In cases like that, one could convert the table to money.
I wonder if you could get a time/money conversion with a revealed preferences sort of method - listing all the tradeoffs you already make and looking for a pattern. It seems like it would at least be useful for noticing if you're being "money pumped" (although consistent does not necessarily equal correct, and time does not necessarily always have equal value).
There was an article a while back about how time doesn't convert directly to money, at least in terms of an hourly wage.
Unless you put yourself in a situation where you can work any time you want, and earn hourly incremental dollars.
I was working two contract jobs at the same time, as I transitioned from one to another. Both sides had an attitude of "give me as many hours as you can". I did a lot of work, because making X dollars and hours usually seemed like time better spent than what I would have otherwise done.
It's hard to manage that kin...
Another gem from xkcd: Is It Worth the Time? It visually answers the question:
Of course, he's not the first person to ask this question, but the visual is handy. Note that the times are calculated assuming you'll save the time over five years.
For example, I've been pondering how to shorten my showers. If I can shave off 1 minute daily, I should be willing to invest up to (but no more than) an entire day to do it. If I think I can shave off five minutes preparing my breakfast, I should be willing to spend up to six days attempting to do so.