Signed through 2012-13 with a $2M cap hit.
Many of the pros for Neil are the same reasons the Senators wouldn't mind keeping him around: Leading, hitting, fighting, and--once in a while--putting points on the board. He's not a consistent scorer, but he is a consistent hustler, and you know what you're going to get from him on any given night. Although he fits in best as a fourth liner, he is a fourth liner who can play, and can easily step up to the third line--maybe even spot duty on the second line, in the right situation. Come playoff time, he's a valuable player to have on your roster.
Within certain team salary structures, Neil's contract may not work for the offensive production he'll bring to a team. It won't be an obstruction for this season, but the two further years on the contract may give potential suitors pause, and lower his trade value in the process.
Moderate. Neil is a player well-suited to playoff hockey, so any team gearing up for an extended playoff run would do well to target a player like Neil for their run. The two years remaining on his contract would lower the return he would otherwise bring, but realistically, any team interested in acquiring Neil would likely earmark him as a potentially valuable asset moving forward.
Nil. I was bordering on marginal, but it would appear that Neil's value to the Senators is higher than it might be to other teams, so Ottawa's asking price would probably be higher than other teams are willing to pay--but I wouldn't at all be surprised if teams inquired about Neil's availability. As the Senators embark on their rebuild, a veteran like Neil on a cap-friendly contract who (literally) bleeds for his team and teammates is the kind of player you like to hold on to. Still, if another team really likes what they see in Neil, it doesn't seem unlikely that they'd pay what it takes to get him (within reason, of course).
Potential trading partners would be teams like the Pittsburgh Penguins, Atlanta Thrashers, Tampa Bay Lightning, New York Rangers, Minnesota Wild, or Phoenix Coyotes: Teams which could use his physical and veteran presence through the playoffs, but also have cap room in the coming few seasons to make room for him.
There aren't really many recently-traded players who bring the sort of mix of physicality and decent play that Neil brings to compare him to, but there are some starting points. Dan Paille, for instance, has a similar offensive capability as Neil, but although he plays in the bottom six, doesn't bring nearly the physical presence Neil does; still, Paille garnered a third-round pick and a conditional fourth-rounder when he was dealt last season. Jason Chimera is the same age as Neil, with less grit but more offence, and was recently traded for a couple of vets in Chris Clark and Milan Jurcina; Ottawa wouldn't want players back, though, and would likely prefer picks or prospects. A final comparable could be Chuck Kobasew, who's a fair bit younger than Neil, somewhat more offensive, and a fair bit less physical; Kobasew was traded for minor-leaguer Craig Weller, prospect Alexander Fallstrom, and a second-round pick.
If I had to guess, I'd think Neil would get an average of those three deals: A second-rounder and a low-payoff prospect wouldn't be out of the realm of possibility, but it would likely be more in the range of a couple of mid-round picks (a third and fourth, perhaps) along with a mid- to low-level prospect or project player.