See my league keeper rules below.
5) Draft Value Keeper League:
5a) Each player drafted receives a Draft Value (DV) equal to the round he was selected. (i.e. - a player selected in the first round has a DV of 1, a player selected in the 13 round has DV of 13).
5b) All undrafted free agent pick-ups have a DV of 9.
5c) A free agent pick-up who was selected during the draft and subsequently released/dropped retains his original DV based on his draft round selection. (i.e. - The brownbaggers select Barry Sanders in the 8th round, his DV is 8. Three weeks later, the Liquid Blues pick him up on the free agent wire for $0.50. His DV stays at 8.)
5d) For each player you decide to keep, you lose a selection in the draft equal to the player's DV. (i.e. - The Pleasures select Robert Smith in the 5th round. His DV is 5 and at the end of the season you subtract 3 leaving him a DV of 2. If the Pleasures decide to keep Robert Smith they will relinquish their 2nd round pick in the next draft.)
5e) If you chose to keep multiple players with the same DV (because of trades and free agent acquisitions) you lose consecutive selections in the draft starting from the lowest DV. (i.e. - The Brownbaggers are going to keep two players with a DV of 4 and one with a DV of 5. The Brownbaggers will have to forfeit their 3rd, 4th, and 5th round selections in the next draft.)
5f) You do not have to retain any players. *The maximum number of players you may retain is 8 which must be consistent with a starting lineup (i.e. - 1 QB, 2 RB, 2 WR, 1 TE, 1 PK and 1 D/ST). Of those six only 1 can be a quarterback.
5g) *Keepers are to be submitted at the draft for that year not sooner.
One warning when moving to a keeper league, be sure to have a solid commissioner because you can see some really strange trades if your commissioner is weak.