Sorry, I'll be more verbose on my requirements this time. and looking at your 
contributions to emacswiki, I can safely assume that such a thing does not exist
if you don't know the answer. 
When browsing file1.c i come to 400th line in function fnA(). I want to remember 
this particular line. so I press F2.  Then I goto file2.c, look  and I don't want to do anything. Then I go to file3.c, and visit line 50 in fnB(). I want to remember this, so I press F2. and so on. 
Now I want to browse through the marked places so I press F3 and F4 to go back 
and forth in the list that I marked. The list now contains two entries 400th line in 
FnA() and 50 the line in FnB().
I can also limit the total number of entries in the list say to 20 or 50. So at most I will
be able to remember 20 or 50 places after which the oldest entries will be 
overwritten. 
Now registers and bookmarks will have tags associated with them and I don't 
want to use tags. I just want to browse through the remembered entries.

Will things-cmd.el serve the purpose ? or is there some other utility ?

Thanks for taking the time to reply.
Maindoor.

--- On Mon, 2/1/10, Drew Adams <drew.adams@oracle.com> wrote:

From: Drew Adams <drew.adams@oracle.com>
Subject: RE: simple requirement, so simple don't know how to search
To: "'Maindoor'" <sanjeevfiles@yahoo.com>, "'Mario Domenech Goulart'" <mario.goulart@gmail.com>
Cc: help-gnu-emacs@gnu.org
Date: Monday, February 1, 2010, 8:52 PM

    Thanks for the info, but registers limit the marked entries
    and I will not be able to cycle through them. So that is 
    out of the question.
    After looking around I found thing-cmds.el . The description
    looks good but I need to try it out.
    I'm looking for something like:
    press F2 -> put the current position where cursor is in a
                  list with limit of 20 entries.
    press F3 -> go forward in the list.
    press F4 -> go backward in the list.

I wrote thing-cmds.el. Dunno if it will help you here - it's not clear to me
what you really want to do. I thought previously that what you wanted was
essentially bookmarks.
 
Now you say you just want to move through a list, that is, move forward a sexp
(list element) at a time. For that you can use `C-M-f', `C-M-b', and so on. What
you mean by your description of F2 is also unclear to me.

People's replies to you have been all over the map, which is an indication that
maybe your requirement isn't well specified. ;-) Most replies take the need to
be to bounce around among predefined positions. Hence people have suggested
marks (and global marks), registers, and bookmarks, all of which let you do
that.