I have heard Memory Lapse trashed so many times its sad! Memory Lapse has always been my favorite card, and I'm going to try and explain why.
Memory Lapse
Counter target spell.
Put it on top of its owners library instead of in their graveyard.
The first thing that jumped out at me when I saw this card was the casting cost.
A cost like that allows it to be put into any deck that can support blue.
The second thing is the disadvantage.
Obviously this card won't be optimal in just any deck, but others can abuse it.
'Turbo Chevy' and 'Blue Chevy' both love this card. Why?
Because the casting cost is great, and the deck draws LOTS of cards in a single turn.
A Memory Lapse in these decks gives you time to search for a better answer.
In my testing I have found Memory Lapse to be priceless in certain combo decks. Why?
Lets say your using a B/R combo or something similar. Memory Lapse allows you to back it up with counters; without totally wrecking your mana base. 4x Memory Lapse and 4x Arcane Denial Can allow you to stall, and protect your combo, and still not slow you down considerably.
Finally, Memory Lapse is flexible. It is a stall counter to the core, but there are times when it is more :~)
It can be used as a really crappy way to keep you from decking an extra turn. Obviously, this is a poor and unreliable method, but you never put Lapse in your deck because of this. It's just a neat bonus trick that will only come in handy 1 out of 1,000 games.
The card can also be used to counter BAD cards. You will find that some opponents will play Raging Goblins on turn 17; even if it will do them no real good. MEMORY LAPSE IT! Teach that guy a lesson for being a poor player. Next turn he'll have to draw it again! Again, this isn't ground breaking, but its nice to know you have the option.
Memory Lapse also has one more trick. It is sometimes a 1U Time Walk. If your opponent taps out to play one card, and you lapse it, then they basicially skipped that turn and showed you the top card of their library! I must stress, I'm not an idiot and I don't think this sort of stuff makes the card good. Its just another way of using it.
So, I hope I've shown that in the proper deck Memory Lapse is VERY good due to its casting cost. Also, in addition, I hope I have shown that it has many tricks that make it valuable in those same decks.
Reasons to use  Memory Lapse
1. You draw ALOT of cards in a single turn and use blue.
2. You want a way to stall, or protect, but don't want to ruin you mana base with UU casting cost stuff.
3. You have one of the above decks, and want some extra situational uses and tricks out of your cards.
I Understand Force of Will, Thwart, Foil, and Counterspell are better in mono blue. I also know that Undermine and Absorb are better if you use the apropriate decks. I was just trying to show Memory Lapse is a Common that CAN be better if used properly with a great CC.
You can E-mail me and I will respond, but don't bother if your going to call me an idiot, or be a real big jack off.
Thanks for reading this far,
Donald Shults